{"id":6400,"date":"2025-12-14T09:53:32","date_gmt":"2025-12-14T00:53:32","guid":{"rendered":"https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/?p=6400"},"modified":"2026-01-09T16:28:43","modified_gmt":"2026-01-09T07:28:43","slug":"%e9%9d%9e%e6%8b%ae%e6%8a%97%e9%98%bb%e5%ae%b3%e3%81%a7%e3%81%afic50-ki","status":"publish","type":"post","link":"https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/2025\/12\/14\/%e9%9d%9e%e6%8b%ae%e6%8a%97%e9%98%bb%e5%ae%b3%e3%81%a7%e3%81%afic50-ki\/","title":{"rendered":"\u975e\u62ee\u6297\u963b\u5bb3\u3067\u306fIC50 = Ki"},"content":{"rendered":"\n\n\n<p>\u5148\u65e5\u306e\u6587\u732e\u30bb\u30df\u30ca\u30fc\u3067\u9175\u7d20\u963b\u5bb3\u5264\u306e\u963b\u5bb3\u69d8\u5f0f\u3068IC<sub>50<\/sub>\u3068<em>K<\/em><sub>i<\/sub>\u306e\u95a2\u4fc2\u306b\u3064\u3044\u3066\u3088\u304f\u5206\u304b\u3063\u3066\u3044\u306a\u304f\u3066\u3001\u9813\u73cd\u6f22\u306a\u8cea\u554f\u3092\u3057\u3066\u3057\u307e\u3063\u305f\u306e\u3067\u30e1\u30e2\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">\u307e\u3068\u3081\uff08\u5f15\u7528\uff09<\/h2>\n\n\n\n<p>\u307e\u305a\u7d50\u8ad6\u3092\u5f15\u7528\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p>IC<sub>50<\/sub>\u3068<em>K<\/em><sub>i<\/sub>\u5024\u306e\u95a2\u4fc2\u306f\u3001in vitro\u306e\u8a66\u9a13\u3067\u306f [<em>S<\/em>] &gt;&gt; <em>K<\/em><sub>m<\/sub>\u304c\u6210\u7acb\u3059\u308b\u306e\u3067\u3001\u975e\u62ee\u6297\u963b\u5bb3\u3084\u4e0d\u62ee\u6297\u963b\u5bb3\u3067\u306fIC<sub>50<\/sub> = <em>K<\/em><sub>i<\/sub>\u3067\u3042\u308a\u3001\u62ee\u6297\u963b\u5bb3\u3067\u306f<em>K<\/em><sub>i<\/sub> = IC<sub>50<\/sub>\/(1 + [<em>S<\/em>]\/<em>K<\/em><sub>m<\/sub>) \u304b\u3089<em>K<\/em><sub>i<\/sub>\u5024\u304c\u63db\u7b97\u3055\u308c\u308b\uff08<em>K<\/em><sub>m<\/sub>: \u30df\u30ab\u30a8\u30ea\u30b9\u5b9a\u6570\u3001<em>K<\/em><sub>i<\/sub>: \u963b\u5bb3\u5b9a\u6570\uff09<br>\u2014 <a href=\"https:\/\/doi.org\/10.11468\/seikatsueisei.54.137\">\u5b89\u9054\u3089\u30012010<\/a><\/p>\n<\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\">\u89e3\u8aac<\/h2>\n\n\n\n<p>\u89e3\u8aac\u3068\u753b\u50cf\u306f<a href=\"https:\/\/doi.org\/10.1177\/2472555219829898\" title=\"\">Buker, S. M., <em>et al.<\/em>, Enzyme\u2013Inhibitor Interactions and a Simple, Rapid Method for Determining Inhibition Modality. <em>SLAS Discovery<\/em> <strong>2019<\/strong>, <em>24<\/em>, 515\u2013522<\/a>\u304b\u3089\u306e\u5f15\u7528\u3067\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>\u5404\u963b\u5bb3\u69d8\u5f0f\u306e\u5b9a\u7fa9\uff08\u7d14\u7c8b\u578b\uff09<\/strong><\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\uff08\u7d14\u7c8b\u306a\uff09<strong>\u62ee\u6297\u963b\u5bb3<\/strong>\uff08competitive inhibition; \u7af6\u5408\u963b\u5bb3\/\u7af6\u4e89\u963b\u5bb3\uff09\u3067\u306f\u3001\u963b\u5bb3\u5264 I \u306f E \u306b\u306e\u307f\u7d50\u5408\u3059\u308b\u3002<\/li>\n\n\n\n<li><strong>\u975e\u62ee\u6297\u963b\u5bb3<\/strong>\uff08non-competitive inhibition; \u975e\u7af6\u5408\u963b\u5bb3\/\u975e\u7af6\u4e89\u963b\u5bb3\uff09\u3067\u306f\u3001\u963b\u5bb3\u5264 I \u306f E \u306b\u3082 ES \u306b\u3082\u540c\u3058\u89aa\u548c\u6027\u3067\u7d50\u5408\u3059\u308b\u3002<\/li>\n\n\n\n<li>\uff08\u7d14\u7c8b\u306a\uff09<strong>\u4e0d\u62ee\u6297\u963b\u5bb3<\/strong>\uff08uncompetitive inhibition; \u4e0d\u7af6\u5408\u963b\u5bb3\/\u4e0d\u7af6\u4e89\u963b\u5bb3\uff09\u3067\u306f\u3001\u963b\u5bb3\u5264 I \u306f ES \u306b\u306e\u307f\u7d50\u5408\u3059\u308b\u3002<\/li>\n<\/ul>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"430\" src=\"https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp\/wp-content\/uploads\/2025\/12\/buker_fig1-1024x430.png\" alt=\"\" class=\"wp-image-6417\" srcset=\"https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp\/wp-content\/uploads\/2025\/12\/buker_fig1-1024x430.png 1024w, https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp\/wp-content\/uploads\/2025\/12\/buker_fig1-300x126.png 300w, https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp\/wp-content\/uploads\/2025\/12\/buker_fig1-768x323.png 768w, https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp\/wp-content\/uploads\/2025\/12\/buker_fig1-1536x646.png 1536w, https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp\/wp-content\/uploads\/2025\/12\/buker_fig1.png 1746w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">Figure 1 from <a href=\"https:\/\/doi.org\/10.1177\/2472555219829898\" title=\"\">Buker, S. M.,<em> et al<\/em>., <strong>2019<\/strong><\/a>. (<strong><a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/\" title=\"\">CC BY-NC-ND 4.0<\/a><\/strong>)<\/figcaption><\/figure>\n\n\n\n<h3 class=\"wp-block-heading\">IC<sub>50<\/sub>\u3068<em>K<\/em><sub>i<\/sub>\u306e\u4e00\u822c\u5f0f<\/h3>\n\n\n\n<p>50%\u963b\u5bb3\u6fc3\u5ea6IC<sub>50<\/sub>\u3068\u963b\u5bb3\u5b9a\u6570<em>K<\/em><sub>i<\/sub>\u306e\u95a2\u4fc2\u306f\u4ee5\u4e0b\u306e\u8fd1\u4f3c\u5f0f\uff08\u5f0f1\uff09\u3067\u8868\u308f\u3055\u308c\u307e\u3059\u3002<\/p>\n\n\n\n<p>\\[ {\\mathrm{IC}}_{50} = \\frac{[S]_0 + K_{\\mathrm m}}{\\frac{K_{\\mathrm m}}{K_{\\mathrm i}} + \\frac{[S]_0}{\\alpha K_{\\mathrm i}}} \\;\\;\\;\\mbox{\u30fb\u30fb\u30fb\u5f0f1}\\]\n\n\n\n<p>\u5f0f1\u306b\u304a\u3044\u3066\u3001\\([S]_0\\) \u306f\u57fa\u8cea\u306e\u521d\u671f\u6fc3\u5ea6\u3092\u8868\u308f\u3057\u307e\u3059: \\([S]_0 = [S] + [ES] + [ESI] + [P] \\)\u3002<\/p>\n\n\n\n<p>\u3053\u306e\u5f0f\u306f\u6df7\u5408\u578b\u963b\u5bb3\uff08mixed-type inhibition; <em>K<\/em><sub>i<\/sub> \u2260 \u03b1<em>K<\/em><sub>i<\/sub>\uff09\u306b\u5bfe\u3059\u308bCheng\u2013Prusoff\u5f0f\uff08<a href=\"https:\/\/doi.org\/10.1016\/0006-2952(73)90196-2\" title=\"\">Cheng and Prusoff, 1973<\/a>\u306eCase II\uff09\u3068\u540c\u4e00\u3067\u3059\u3002\u963b\u5bb3\u69d8\u5f0f\u3092\u89e3\u6790\u3059\u308b\u76ee\u7684\u3067\u3001IC<sub>50<\/sub>\u3092 [<em>S<\/em>]<sub>0<\/sub>\/<em>K<\/em><sub>m<\/sub>\u306b\u5bfe\u3057\u3066\u30d7\u30ed\u30c3\u30c8\u3057\u305f\u3044\u306e\u3067\u3001\u5f0f1\u3092\u5909\u5f62\u3059\u308b\u3068\u6b21\u306e\u3088\u3046\u306b\u306a\u308a\u307e\u3059\u3002 $$ {\\mathrm{IC}}_{50} = \\frac{1 + \\frac{[S]_0}{K_{\\mathrm m}}}{\\frac{1}{K_{\\mathrm i}} + \\left(\\frac{1}{\\alpha K_{\\mathrm i}} \\times \\frac{[S]_0}{K_{\\mathrm m}}\\right)} $$<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u5404\u963b\u5bb3\u69d8\u5f0f\u3067\u306e\u6975\u9650<\/h3>\n\n\n\n<p><strong>\u62ee\u6297\u963b\u5bb3<\/strong>\uff08\\(\\alpha\\to \\infty\\)\uff09<\/p>\n\n\n\n<p>$$ {\\mathrm{IC}}_{50} = \\frac{1 + \\frac{[S]}{K_{\\mathrm m}}}{\\frac{1}{K_{\\mathrm i}}} = K_{\\mathrm i} \\left(1 + \\frac{[S]}{K_{\\mathrm m}}\\right)$$<\/p>\n\n\n\n<p><strong>\u975e\u62ee\u6297\u963b\u5bb3<\/strong>\uff08\\(\\alpha =  1\\)\uff09<\/p>\n\n\n\n<p>$$ {\\mathrm{IC}}_{50} = K_{\\mathrm i}$$<\/p>\n\n\n\n<p><strong>\u4e0d\u62ee\u6297\u963b\u5bb3<\/strong>\uff08\\(K_{\\mathrm i}\\to \\infty\\)\u3001\u305f\u3060\u3057\\( \\alpha K_{\\mathrm i}\\) \u304c\u6709\u9650\u306e\u5834\u5408\uff09<\/p>\n\n\n\n<p>$$ {\\mathrm{IC}}_{50} = \\alpha K_{\\mathrm i} \\left(1 + \\frac{K_{\\mathrm m}}{[S]}\\right)$$<\/p>\n\n\n\n<p>\u7279\u306b\\([S] \\gg K_{\\mathrm m}\\)\u306e\u6761\u4ef6\u4e0b\u3067\u306f\u3001<\/p>\n\n\n\n<p>$$ \\mathrm{IC}_{50} \\sim \\alpha K_{\\mathrm i} $$<\/p>\n\n\n\n<p>\u307e\u3068\u3081\u306e\u8868:<\/p>\n\n\n\n<figure class=\"wp-block-table is-style-stripes\"><table><thead><tr><th>\u963b\u5bb3\u6a5f\u69cb<\/th><th>\u30d1\u30e9\u30e1\u30fc\u30bf<\/th><th>IC<sub>50<\/sub><\/th><\/tr><\/thead><tbody><tr><td>\u62ee\u6297\uff08competitive\uff09<\/td><td>\\(\\alpha\\to \\infty \\)<\/td><td>\\( K_{\\mathrm i} \\left(1 + \\frac{[S]}{K_{\\mathrm m}}\\right)\\)<\/td><\/tr><tr><td>\u975e\u62ee\u6297\uff08non-competitive\uff09<\/td><td>\\( \\alpha = 1 \\)<\/td><td>\\( K_{\\mathrm i}\\)<\/td><\/tr><tr><td>\u4e0d\u62ee\u6297\uff08uncompetitive\uff09<\/td><td>\\(K_{\\mathrm i}\\to \\infty\\)\u3001\\( \\alpha K_{\\mathrm i} \\ll K_{\\mathrm i}\\)<\/td><td>\\( \\alpha K_{\\mathrm i} \\left(1 + \\frac{K_{\\mathrm m}}{[S]}\\right)\\)<\/td><\/tr><tr><td>\u6df7\u5408\uff08mixed\uff09<\/td><td>&#8211;<\/td><td>\\( \\frac{[S] + K_{\\mathrm m}}{\\frac{K_{\\mathrm m}}{K_{\\mathrm i}} + \\frac{[S]}{\\alpha K_{\\mathrm i}}} \\)<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p>\u305d\u308c\u305e\u308c\u306e\u963b\u5bb3\u69d8\u5f0f\u306b\u3064\u3044\u3066\u3001 [<em>S<\/em>]\/<em>K<\/em><sub>m<\/sub>\u306b\u5bfe\u3057\u3066IC<sub>50<\/sub>\u3092\u30d7\u30ed\u30c3\u30c8\u3057\u305f\u3082\u306e\u304c\u4ee5\u4e0b\u306e\u56f3\u3067\u3059\u3002<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"915\" src=\"https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp\/wp-content\/uploads\/2025\/12\/buker_fig5-1024x915.png\" alt=\"\" class=\"wp-image-6418\" srcset=\"https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp\/wp-content\/uploads\/2025\/12\/buker_fig5-1024x915.png 1024w, https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp\/wp-content\/uploads\/2025\/12\/buker_fig5-300x268.png 300w, https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp\/wp-content\/uploads\/2025\/12\/buker_fig5-768x686.png 768w, https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp\/wp-content\/uploads\/2025\/12\/buker_fig5.png 1312w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">Figure 5 from <a href=\"https:\/\/doi.org\/10.1177\/2472555219829898\" title=\"\">Buker, S. M.,<em> et al<\/em>., <strong>2019<\/strong><\/a>. (<strong><a href=\"https:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/\" title=\"\">CC BY-NC-ND 4.0<\/a><\/strong>)<\/figcaption><\/figure>\n\n\n\n<p>\u30bb\u30df\u30ca\u30fc\u3067\u7d39\u4ecb\u3055\u308c\u305f\u8ad6\u6587\u3067\u306f\u3053\u306e\u30d7\u30ed\u30c3\u30c8\u304c &#8220;Cheng\u2013Prusoff plot&#8221; \u3068\u547c\u3070\u308c\u3066\u3044\u307e\u3057\u305f\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">\u5f0f1\u306e\u5c0e\u51fa<\/h2>\n\n\n\n<p>\u5c0e\u51fa\u306f<a href=\"https:\/\/doi.org\/10.1016\/0006-2952(73)90196-2\" title=\"\">Cheng and Prusoff, 1973<\/a>\u306eCase II\u304b\u3089\u3002<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"398\" src=\"https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp\/wp-content\/uploads\/2025\/12\/noncompetitive-1024x398.png\" alt=\"\" class=\"wp-image-6429\" srcset=\"https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp\/wp-content\/uploads\/2025\/12\/noncompetitive-1024x398.png 1024w, https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp\/wp-content\/uploads\/2025\/12\/noncompetitive-300x117.png 300w, https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp\/wp-content\/uploads\/2025\/12\/noncompetitive-768x299.png 768w, https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp\/wp-content\/uploads\/2025\/12\/noncompetitive.png 1502w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<p>\u53cd\u5fdc\u7cfb\u306f\u8fc5\u901f\u306b\u5e73\u8861\u306b\u9054\u3059\u308b\u3068\u4eee\u5b9a\u3057\u307e\u3059\u3002\u3057\u305f\u304c\u3063\u3066\u3001\\(k_{-1} \\gg k_{cat} \\) \u306a\u306e\u3067\u3001\\(K_{\\mathrm{s}} = K_{\\mathrm{m}} + \\frac{k_{cat}}{k_{-1}} \\sim K_{\\mathrm{m}} \\) \u304c\u6210\u308a\u7acb\u3061\u307e\u3059\u3002 <\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u5b9a\u7fa9\u5f0f<\/h3>\n\n\n\n<p>$$ K_{\\mathrm{m}} \\sim K_{\\mathrm{s}} = \\frac{[E][S]}{[ES]} \\;\\;\\;\\mbox{\u30fb\u30fb\u30fb\u5f0f2}$$<\/p>\n\n\n\n<p>$$ K_{\\mathrm{i}} = \\frac{[E][I]}{[EI]} \\;\\;\\;\\mbox{\u30fb\u30fb\u30fb\u5f0f3}$$<\/p>\n\n\n\n<p>$$ \\alpha K_{\\mathrm{i}} = \\frac{[ES][I]}{[ESI]} \\;\\;\\;\\mbox{\u30fb\u30fb\u30fb\u5f0f4}$$<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u963b\u5bb3\u5264\u304c\u5b58\u5728\u3057\u306a\u3044\u5834\u5408<\/h3>\n\n\n\n<p>$$ V_0 = \\frac{V_{\\mathrm{max}} [S]}{K_{\\mathrm{m}} + [S]}$$<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u963b\u5bb3\u5264\u304c\u5b58\u5728\u3059\u308b\u5834\u5408<\/h3>\n\n\n\n<p>\u9175\u7d20\u6fc3\u5ea6\u306e\u4fdd\u5b58\u5247\u306f<\/p>\n\n\n\n<p>$$ [E]_0 = [E] + [ES] + [EI] + [ESI] \\;\\;\\;\\mbox{\u30fb\u30fb\u30fb\u5f0f5}$$<\/p>\n\n\n\n<p>\u5f0f5\u306b\u5f0f3\u304a\u3088\u3073\u5f0f4\u3092\u4ee3\u5165\u3059\u308b\u3068<\/p>\n\n\n\n<p>$$[E]_0 = [E] + [ES] + \\frac{[E] [I]}{K_{\\mathrm{i}}} + \\frac{[ES][I]}{\\alpha K_{\\mathrm{i}}} \\;\\;\\;\\mbox{\u30fb\u30fb\u30fb\u5f0f6}$$<\/p>\n\n\n\n<p>\u3068\u306a\u308a\u307e\u3059\u3002\u3053\u308c\u3092\u5909\u5f62\u3059\u308b\u3068<\/p>\n\n\n\n<p>$$ [E] = \\frac{[E]_0 &#8211; \\left( 1 + \\frac{[I]}{\\alpha K_{\\mathrm{i}}}\\right) [ES] }{ 1 + \\frac{[I]}{K_{\\mathrm{i}}}} \\;\\;\\;\\mbox{\u30fb\u30fb\u30fb\u5f0f7}$$<\/p>\n\n\n\n<p>\u3068\u306a\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<p>\u5f0f2\u3068\u5f0f7\u3092\u9023\u7acb\u3057\u3066 [ES] \u306b\u3064\u3044\u3066\u89e3\u304f\u3068<\/p>\n\n\n\n<p>$$ [ES] = \\frac{[E]_0 [S]}{K_{\\mathrm{m}}\\left(1+ \\frac{[I]}{K_{\\mathrm{i}} }\\right) + [S] \\left( 1 + \\frac{[I]}{\\alpha K_{\\mathrm{i}} }\\right)}  $$<\/p>\n\n\n\n<p>\u3068\u306a\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<p>\u3057\u305f\u304c\u3063\u3066\u963b\u5bb3\u5264\u304c\u5b58\u5728\u3059\u308b\u6642\u306e\u53cd\u5fdc\u901f\u5ea6 \\(V_I \\)\uff08\\(V_I = k_{cat} [ES]\\)\u3001\\(k_{cat} [E]_0 = V_{\\mathrm{max}}\\)\uff09\u306f<\/p>\n\n\n\n<p>$$ V_I = \\frac{V_{\\mathrm{max}} [S]}{K_{\\mathrm{m}}\\left(1+ \\frac{[I]}{K_{\\mathrm{i}} }\\right) + [S] \\left( 1 + \\frac{[I]}{\\alpha K_{\\mathrm{i}} }\\right)} $$<\/p>\n\n\n\n<p>\u3068\u8868\u308f\u3055\u308c\u307e\u3059\u3002<\/p>\n\n\n\n<p>\\( [I] = [I]_{50}\\) \u306e\u6642\u3001\\( V_0 = 2 V_I \\) \u3067\u3042\u308b\u305f\u3081\u3001<\/p>\n\n\n\n<p>$$ \\frac{V_{\\mathrm{max}} [S]}{K_{\\mathrm{m}} + [S]} = \\frac{2 V_{\\mathrm{max}} [S]_{50}}{K_{\\mathrm{m}}\\left(1+ \\frac{[I]_{50}}{K_{\\mathrm{i}} }\\right) + [S]_{50} \\left( 1 + \\frac{[I]_{50}}{\\alpha K_{\\mathrm{i}} }\\right)} $$<\/p>\n\n\n\n<p>\u3068\u3044\u3046\u95a2\u4fc2\u5f0f\u304c\u5f97\u3089\u308c\u307e\u3059\u3002\u3053\u306e\u5f0f\u3092\u5909\u5f62\u3059\u308b\u3068<\/p>\n\n\n\n<p>$$[I]_{50} = \\frac{[S]_{50} + 2\\frac{[S]_{50}}{[S]}K_{\\mathrm m} &#8211; K_{\\mathrm m}}{ \\frac{K_{\\mathrm m}}{K_{\\mathrm i}} + \\frac{[S]_{50}}{\\alpha K_{\\mathrm i}}}$$<\/p>\n\n\n\n<p>\u3068\u306a\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<p>\u57fa\u8cea\u6fc3\u5ea6\u304c\u9175\u7d20\u6fc3\u5ea6\u306b\u5bfe\u3057\u3066\u5341\u5206\u5927\u304d\u3051\u308c\u3070\u3001\u904a\u96e2\u578b\u57fa\u8cea\u6fc3\u5ea6\\([S]\\)\u304a\u3088\u3073\\([S]_{50}\\)\u3092\u521d\u671f\u6fc3\u5ea6\\([S]_0\\)\u3067\u8fd1\u4f3c\u3067\u304d\u308b\u306e\u3067\u3001\u4e0a\u5f0f\u306e\\([S]\\)\u304a\u3088\u3073\\([S]_{50}\\)\u3092\\([S]_0\\)\u306b\u7f6e\u63db\u3057\u3066\u304b\u3089\u4e0a\u5f0f\u3092\u5909\u5f62\u3059\u308b\u3068<\/p>\n\n\n\n<p>$$ [I]_{50} = \\frac{[S]_0 + K_{\\mathrm{m}} }{\\frac{K_{\\mathrm{m}}}{K_{\\mathrm{i}}} + \\frac{[S]_0}{\\alpha K_{\\mathrm{i}} } } $$<\/p>\n\n\n\n<p>\u3068\u306a\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<p>\u3055\u3089\u306b\u3001\u963b\u5bb3\u5264\u6fc3\u5ea6\u304c\u9175\u7d20\u6fc3\u5ea6\u306b\u5bfe\u3057\u3066\u5341\u5206\u306b\u904e\u5270\uff08\\([I] \\gg [EI] + [ESI]\\)\uff09\u3067\u3042\u308c\u3070\u3001\u904a\u96e2\u578b\u963b\u5bb3\u5264\u6fc3\u5ea6 \\( [I]_{50}\\) \u3092\u5168\u963b\u5bb3\u5264\u6fc3\u5ea6 \\(\\mathrm{IC}_{50} \\) \u3067\u8fd1\u4f3c\u3067\u304d\u3001<\/p>\n\n\n\n<p>$$ \\mathrm{IC}_{50} = \\frac{[S]_0 + K_{\\mathrm{m}} }{\\frac{K_{\\mathrm{m}}}{K_{\\mathrm{i}}} + \\frac{[S]_0}{\\alpha K_{\\mathrm{i}} } } \\;\\;\\;\\mbox{\u30fb\u30fb\u30fb\u5f0f1}$$<\/p>\n\n\n\n<p>\u5f0f1\u304c\u5c0e\u304b\u308c\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u53c2\u8003\u6587\u732e<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u5b89\u9054\u5f25\u6c38, \u5b89\u4fdd\u667a\u5b50,&nbsp;\u85e4\u5cf6\u7f8e\u7d00,&nbsp;\u6e21\u908a\u6cbb\u592b\u3001\u30d2\u30c8\u809d\u30df\u30af\u30ed\u30bd\u30fc\u30e0\u306e\u30c1\u30c8\u30af\u30ed\u30fc\u30e0P-450\u6d3b\u6027\u3078\u306e\u30b9\u30ae\u30ca\u30a8\u30ad\u30b9\u306e\u5f71\u97ff\u3068\u8840\u4e2d\u85ac\u5264\u3068\u306e\u76f8\u4e92\u4f5c\u7528\u4e88\u6e2c. \u751f\u6d3b\u885b\u751f <strong>2010<\/strong>, <em>54<\/em>, 137\u2013145. DOI: <a href=\"https:\/\/doi.org\/10.11468\/seikatsueisei.54.137\">10.11468\/seikatsueisei.54.137<\/a><\/li>\n\n\n\n<li>Buker, S. M.; Boriack\u2013Sjodin, P. A.; Copeland, R. A. Enzyme\u2013Inhibitor Interactions and a Simple, Rapid Method for Determining Inhibition Modality. <em>SLAS Discovery<\/em> <strong>2019<\/strong>, <em>24<\/em>, 515\u2013522. DOI: <a href=\"https:\/\/doi.org\/10.1177\/2472555219829898\">10.1177\/2472555219829898<\/a><\/li>\n\n\n\n<li>Cheng, Y.- C.; Prusoff, W. H. Relationship between the inhibition constant (<em>K<\/em><sub><em>I<\/em><\/sub>) and the concentration of inhibitor which causes 50 per cent inhibition (<em>I<\/em><sub>50<\/sub>) of an enzymatic reaction. <em>Biochem. Pharmacol.<\/em> <strong>1973<\/strong>, <em>22<\/em>, 3099\u20133108. DOI: <a href=\"https:\/\/doi.org\/10.1016\/0006-2952(73)90196-2\">10.1016\/0006-2952(73)90196-2<\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/www.promega.co.jp\/docs_category\/%E3%83%86%E3%83%83%E3%82%AF%E3%81%AE%E4%B8%80%E8%A8%80%E3%82%B3%E3%83%A9%E3%83%A0_2015%E5%B9%B49%E6%9C%88%E5%8F%B7-%E3%81%93%E3%82%8C%E3%81%8B%E3%82%89%E5%89%B5%E8%96%AC%E3%82%92%E5%A7%8B\/\" title=\"\">\u30d7\u30ed\u30e1\u30ac\u682a\u5f0f\u4f1a\u793e\u300c\u30c6\u30c3\u30af\u306e\u4e00\u8a00\u30b3\u30e9\u30e0_2015\u5e749\u6708\u53f7 \u3053\u308c\u304b\u3089\u5275\u85ac\u3092\u59cb\u3081\u308b\u65b9\u3078 \uff5e \u9175\u7d20\u963b\u5bb3\u5264\u7de8 \uff5e\u300d<\/a>(2025\u5e7412\u670816\u65e5\u95b2\u89a7).<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Ki\u304c\u975e\u5e38\u306b\u5c0f\u3055\u3044\u963b\u5bb3\u5264\uff08Tight-binding inhibitor\uff09\u306e\u5834\u5408<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">\u307e\u3068\u3081\uff08\u5f15\u7528\uff09<\/h3>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p>\u5f37\u3044\u963b\u5bb3\u5264\uff08\\([I] \\approx [E]\\)\uff09\u306eK<sub>i<\/sub>\u306e\u5177\u4f53\u7684\u306a\u7b97\u51fa\u306b\u306f\uff0c\u7dda\u5f62\u578b\u306eHenderson\u30d7\u30ed\u30c3\u30c8\uff0c\u3042\u308b\u3044\u306fMorrison\u306e\u5f0f\u3092\u7528\u3044\u305f\u975e\u7dda\u5f62\u56de\u5e30\u5206\u6790\u3092\u884c\u3046\uff0e\u305f\u3060\u3057\uff0cHenderson\u30d7\u30ed\u30c3\u30c8\u3084Morrison\u306e\u5f0f\u304b\u3089\u6c42\u307e\u308b\u3082\u306e\u306f\u898b\u304b\u3051\u306e \\(K_{\\mathrm{i}}\\)\uff08\\(K^{\\mathrm{app}}_{\\mathrm{i}}\\)\uff09\u3067\u3042\u308a, &#8230; \\(K_{\\mathrm{i}}\\)\u3078\u306e\u5909\u63db\u3092\u8981\u3059\u308b\uff0e<\/p>\n\n\n\n<p>\u2014 <a href=\"https:\/\/www.sbj.or.jp\/sbj\/sbj_vol92_no01.html\" title=\"\">\u77e5\u540d\u79c0\u6cf0\u30fb\u5ca1\u7530\u8c4a\u30012014<\/a><\/p>\n<\/blockquote>\n\n\n\n<h3 class=\"wp-block-heading\">Morrison\u306e\u5f0f<\/h3>\n\n\n\n<p>\u904a\u96e2\u578b\u963b\u5bb3\u5264\u6fc3\u5ea6 \\( [I]\\) \u3092\u5168\u963b\u5bb3\u5264\u6fc3\u5ea6 \\([I]_{\\mathrm{T}} \\) \u3067\u8fd1\u4f3c\u3067\u304d\u306a\u3044\u5834\u5408\u3001Morrison\u306e\u5f0f\uff08Morrison equation\uff09\u3092\u4f7f\u3063\u3066\u3001\u975e\u7dda\u5f62\u56de\u5e30\u5206\u6790\u306b\u3088\u308a\u898b\u304b\u3051\u306e \\(K_{\\mathrm{i}}\\)\u5024\uff08 \\(K^{\\mathrm{app}}_{\\mathrm{i}}\\)\uff09\u3092\u6c42\u3081\u308b\uff08<a href=\"https:\/\/doi.org\/10.1016\/0005-2744(69)90420-3\" title=\"\">Morrison, 1969<\/a>; <a href=\"https:\/\/doi.org\/10.1002\/0471220639.ch9\" title=\"\">Copeland, 2000<\/a>\uff09\u3002 <\/p>\n\n\n\n<p>$$ \\frac{V_I}{V_0} = 1 &#8211; \\frac{ ([E]_0 + [I]_{\\mathrm{T}}) +  K^{\\mathrm{app}}_{\\mathrm{i}} ) &#8211; \\sqrt{  ([E]_0 + [I]_{\\mathrm{T}}) +  K^{\\mathrm{app}}_{\\mathrm{i}} )^2 &#8211; 4 [E]_0  [I]_{\\mathrm{T}} } }{ 2 [E]_0 } $$<\/p>\n\n\n\n<p>\u62ee\u6297\u963b\u5bb3: $$  K^{\\mathrm{app}}_{\\mathrm{i}} = K_{\\mathrm{i}} \\left( 1 + \\frac{[S]}{K_{\\mathrm{m}}} \\right)$$<\/p>\n\n\n\n<p>\u975e\u62ee\u6297\u963b\u5bb3: $$  K^{\\mathrm{app}}_{\\mathrm{i}} = \\frac{\\alpha K_{\\mathrm{i}} (K_{\\mathrm{m}} + [S] )}{\\alpha K_{\\mathrm{m}} + [S]} $$ \\(\\alpha = 1\\) \u306e\u6642: $$K^{\\mathrm{app}}_{\\mathrm{i}} = K_{\\mathrm{i}}  $$<\/p>\n\n\n\n<p>\u4e0d\u62ee\u6297\u963b\u5bb3: $$ K^{\\mathrm{app}}_{\\mathrm{i}} = K_{\\mathrm{i}} \\left( 1 + \\frac{K_{\\mathrm{m}}} {[S]}\\right)$$<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u53c2\u8003\u6587\u732e<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u77e5\u540d\u79c0\u6cf0, \u5ca1\u7530\u8c4a\u3001\u7d9a\u30fb\u751f\u7269\u5de5\u5b66\u57fa\u790e\u8b1b\u5ea7 \u30d0\u30a4\u30aa\u3088\u3082\u3084\u307e\u8a71 \u539f\u5178\u304b\u3089\u306e\u9175\u7d20\u53cd\u5fdc\u901f\u5ea6\u8ad6. \u751f\u7269\u5de5\u5b66\u4f1a\u8a8c <strong>2014<\/strong>, <em>92<\/em>, 20\u201325. <a href=\"https:\/\/www.sbj.or.jp\/sbj\/sbj_vol92_no01.html\">https:\/\/www.sbj.or.jp\/sbj\/sbj_vol92_no01.html<\/a><\/li>\n\n\n\n<li>Morrison , J. F. Kinetics of the reversible inhibition of enzyme-catalysed reactions by tight-binding inhibitors. <em>Biochim. Biophys. Acta<\/em>, <em>Enzymol<\/em>. <strong>1969<\/strong>, <em>185<\/em>, 269\u2013286. DOI: <a href=\"https:\/\/doi.org\/10.1016\/0005-2744(69)90420-3\" title=\"\">10.1016\/0005-2744(69)90420-3<\/a><\/li>\n\n\n\n<li>Copeland, R. A. Tight-binding inhibitor. <em>Enzymes: A Practical Introduction to Structure, Mechanism, and Data Analysis<\/em>, 2nd ed.; Wiley, 2000, 205\u2013317. DOI: <a href=\"https:\/\/doi.org\/10.1002\/0471220639.ch9\" title=\"\">10.1002\/0471220639.ch9<\/a><\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">\u57fa\u8cea\u3068\u963b\u5bb3\u5264\u306e\u4e21\u65b9\u304cTight-binding\u306e\u5834\u5408<\/h2>\n\n\n\n<p>\u9175\u7d20\u963b\u5bb3\u5264\u8907\u5408\u4f53\u306e\u6fc3\u5ea6 [EI] \u306f\u4ee5\u4e0b\u306e\u5f0f\u3067\u8868\u308f\u3055\u308c\u308b\uff08<a href=\"https:\/\/doi.org\/10.1016\/0014-5793(95)00062-E\" title=\"\">Wang, 1995<\/a>\uff09\u3002<\/p>\n\n\n\n<p>$$ [EI] = \\frac{ [I]_{\\mathrm{T}} \\{2\\sqrt{(a^2 &#8211; 3b)} \\cos (\\Theta\/3) &#8211; a \\} }{ 3K_{\\mathrm{i}} + \\{2\\sqrt{(a^2 &#8211; 3b)} \\cos (\\Theta\/3) &#8211; a \\} } $$<\/p>\n\n\n\n<p>\u4e0a\u5f0f\u306b\u304a\u3044\u3066\u3001<\/p>\n\n\n\n<p>$$ a = K_{\\mathrm{s}} + K_{\\mathrm{i}} + [S]_{\\mathrm{T}} + [I]_{\\mathrm{T}} &#8211; [E]_{\\mathrm{T}} $$<\/p>\n\n\n\n<p>$$ b = K_{\\mathrm{i}} ([S]_{\\mathrm{T}} &#8211; [E]_{\\mathrm{T}}) + K_{\\mathrm{s}} ([I]_{\\mathrm{T}} &#8211; [E]_{\\mathrm{T}}) + K_{\\mathrm{s}} K_{\\mathrm{i}} $$<\/p>\n\n\n\n<p>$$ c = -K_{\\mathrm{s}} K_{\\mathrm{i}} [E]_{\\mathrm{T}} $$<\/p>\n\n\n\n<p>$$ \\Theta = \\arccos \\frac{-2a^3 + 9ab &#8211; 27c}{2\\sqrt{(a^2-3b)^3}} $$<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u53c2\u8003\u6587\u732e<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Wang, Z.-X. An exact mathematical expression for describing competitive binding of two different ligands to a protein molecule. <em>FEBS Lett.<\/em> <strong>1995<\/strong>, <em>360<\/em>, 111\u2013114. DOI: <a href=\"https:\/\/doi.org\/10.1016\/0014-5793(95)00062-E\" title=\"\">10.1016\/0014-5793(95)00062-E<\/a><\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>\u5148\u65e5\u306e\u6587\u732e\u30bb\u30df\u30ca\u30fc\u3067\u9175\u7d20\u963b\u5bb3\u5264\u306e\u963b\u5bb3\u69d8\u5f0f\u3068IC50\u3068Ki\u306e\u95a2 &#8230;<\/p>\n","protected":false},"author":1,"featured_media":6429,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"om_disable_all_campaigns":false,"_uag_custom_page_level_css":"","_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"_uf_show_specific_survey":0,"_uf_disable_surveys":false,"_locale":"ja","_original_post":"https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/?p=6400","footnotes":""},"categories":[9],"tags":[],"class_list":["post-6400","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-9","ja"],"aioseo_notices":[],"uagb_featured_image_src":{"full":["https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp\/wp-content\/uploads\/2025\/12\/noncompetitive.png",1502,584,false],"thumbnail":["https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp\/wp-content\/uploads\/2025\/12\/noncompetitive-150x150.png",150,150,true],"medium":["https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp\/wp-content\/uploads\/2025\/12\/noncompetitive-300x117.png",300,117,true],"medium_large":["https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp\/wp-content\/uploads\/2025\/12\/noncompetitive-768x299.png",768,299,true],"large":["https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp\/wp-content\/uploads\/2025\/12\/noncompetitive-1024x398.png",800,311,true],"1536x1536":["https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp\/wp-content\/uploads\/2025\/12\/noncompetitive.png",1502,584,false],"2048x2048":["https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp\/wp-content\/uploads\/2025\/12\/noncompetitive.png",1502,584,false],"onepress-blog-small":["https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp\/wp-content\/uploads\/2025\/12\/noncompetitive-300x150.png",300,150,true],"onepress-small":["https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp\/wp-content\/uploads\/2025\/12\/noncompetitive-480x300.png",480,300,true],"onepress-medium":["https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp\/wp-content\/uploads\/2025\/12\/noncompetitive-640x400.png",640,400,true]},"uagb_author_info":{"display_name":"RCY","author_link":"https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/author\/charlesy\/"},"uagb_comment_info":0,"uagb_excerpt":"\u5148\u65e5\u306e\u6587\u732e\u30bb\u30df\u30ca\u30fc\u3067\u9175\u7d20\u963b\u5bb3\u5264\u306e\u963b\u5bb3\u69d8\u5f0f\u3068IC50\u3068Ki\u306e\u95a2 ...","_links":{"self":[{"href":"https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp-json\/wp\/v2\/posts\/6400","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp-json\/wp\/v2\/comments?post=6400"}],"version-history":[{"count":58,"href":"https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp-json\/wp\/v2\/posts\/6400\/revisions"}],"predecessor-version":[{"id":6656,"href":"https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp-json\/wp\/v2\/posts\/6400\/revisions\/6656"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp-json\/wp\/v2\/media\/6429"}],"wp:attachment":[{"href":"https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp-json\/wp\/v2\/media?parent=6400"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp-json\/wp\/v2\/categories?post=6400"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ag.kagawa-u.ac.jp\/charlesy\/wp-json\/wp\/v2\/tags?post=6400"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}