Name: graphing enzyme kinetics data
Uploaded: 2023-04-30T10:09:42.000Z
Duration: 1 min 19 s
Channel: JoVE

K12 Standards

north-carolina-k-12-science-standard-course-of-study

North Carolina K-12 Science Standard Course of Study

9-12

Biology

from-molecules-to-organisms-structures-and-processes

From Molecules to Organisms- Structures and Processes

LS.Bio.1.2

Introduction to Enzyme Kinetics

تدرس حركية الإنزيم معدلات التفاعلات المحفزة بالإنزيم. تتم مراقبة معدلات التجارب المتكررة بتركيزات ركيزة متفاوتة عن طريق قياس تركيز الركيزة المستهلكة أو المنتج المتكون بمرور الوقت.
يمكن رسم هذه النتائج بيانيا لإظهار كيفية تأثير تركيز الركيزة على معدل أو سرعة التفاعل.
تزداد سرعة التفاعل خطيا مع زيادة كميات الركيزة بتركيزات منخفضة ، لكنها تبدأ في الاستقرار بتركيزات أعلى. يقترب المعدل من السرعة القصوى أو Vmax - المعدل الذي يكون فيه الإنزيم مشبعا تماما بالركيزة.
يقيس تقارب الإنزيم مدى قوة أو ضعف ارتباط الإنزيم بركيسته ويتم قياسه كميا بواسطة KM ، ثابت Michaelis. قيمة KM تساوي تركيز الركيزة عندما يكون المعدل 50٪ من Vكحد أقصى.
يشير KM الصغير إلى أن الإنزيم له تقارب ركيزة مرتفع والعكس صحيح. يتطلب الإنزيم الذي يحتوي على KM أكبر تركيزات ركيزة أعلى للاقتراب من سرعته القصوى مقارنة بالإنزيم الذي يحتوي على KM أقل.

<ol>
	<li>Voet D. and Voet J.G. الكيمياء الحيوية ، الطبعة الرابعة John Wiley & Sons ، 2010 pp-487-492</li>
	<li>بيرج جي إم ، تيموتشكو جي إل ، وستراير إل الكيمياء الحيوية ، الطبعة الخامسة ، دبليو إتش فريمان وشركاه ، القسم 8.4</li>
</ol>

مقدمة في الحركية الانزيماتية

<div style="direction: rtl;">
تدرس حركية الإنزيمات نسب التقدم التي تتم بها التفاعلات الكيميائية الحيوية. يراقب العلماء هذه النسبة في التفاعلات الأنزيمية بوجود بتركيزات مختلفة من الركيزة. كما تجرى أيضا تجارب إضافية باستخدام مثبطات أو جزيئات أخرى بإمكانها أن تؤثر على نسبة تقدم التفاعل.

يمكن للباحث بعد ذلك رسم معدل التفاعل الأولي أو السرعة (V_o) لتجربة معينة مقابل تركيز الركيزة ([S]) للحصول على رسم بياني يلخص خصائص التفاعل. بالنسبة للعديد من التفاعلات الأنزيمية التي تتضمن ركيزة واحدة، فإن هذه البيانات تناسب معادلة ميكايليس-مينتن، وهي معادلة مشتقة من ليونور ميكايليس ومود مينتن.

<img alt="Eq1" src="/files/ftp_upload/12164/12164_Equation 1.png" style="text-align: center; height: 70px;" />

تمكن المعادلة من تقدير السرعة القصوى (V_max) وثابتة ميكايليس (KM) للإنزيم قيد الدراسة وتنطلق من الافتراضات التالية:

<ol>
	<li>لا يوجد أي ناتج في بداية التفاعل.</li>
	<li>معدل تكوين مركب الإنزيم والركيزة يساوي معدل التفكك والتحلل إلى نواتج.</li>
	<li>تركيز الإنزيم ضئيل مقارنة بتركيز الركيزة.</li>
	<li>يتم قياس معدلات التفاعل الأولية فقط.</li>
	<li>الإنزيم موجود إما في شكل حر أو ضمن مجمع الإنزيم الركيزة.</li>
</ol>

تُعد عمليات إعادة الترتيب المختلفة لمعادلة ميكايليس-مينتن، مثل مخططات Lineweaver-Burke وEadie-Hofsteot وHanes-Woolf، طرقًا بديلة لرسم المعلمات الحركية بيانيًا. غالبًا ما يتم استخدام مخطط Lineweaver-Burke أو المخطط التبادلي المزدوج لتقدير ثابتة ميكايليس KM والسرعة القصوى V_max. يستخدم المخطط القيم التبادلية للمحور x و y من مخطط Michaelis-Menten. رياضياً، تقاطع y يساوي واحد مقسوم على السرعة القصوى، وتقاطع x يساوي سالب واحد مقسوم على ثابتة ميكايليس.

يمكن استخدام مخطط Lineweaver-Burke للتمييز بشكل مرئي بين أنواع المثبطات - التنافسية، وغير التنافسية، وغير القابلة للتنافس. تُستخدم أيضًا عمليات إعادة ترتيب مختلفة لمعادلة ميكايليس-مينتن، مثل مخططات إيدي-هوفستي وهانس-وولف، لتحديد المعلمات الحركية.
</div>

تدرس حركية الإنزيم معدلات التفاعلات الكيميائية الحيوية. يراقب العلماء معدلات التفاعل لتفاعل إنزيمي معين في ركيزة مختلفة ...

Education

JoVE Core

Cell Biology

بيولوجيا الخلية

Unit 1

الوحدة الأولى

Energy and Catalysis

الطاقة والتحفيز

KEY TERMS AND CONCEPTS

المصطلحات والمفاهيم الأساسية

graphing enzyme kinetics data

Enzyme kinetics uses graphs to show how fast a biochemical reaction happens. Scientists measure the initial reaction rate, or velocity (Vo), at different substrate concentrations ([S]). They may also run trials with inhibitors or other molecules that change the reaction rate.

The results are often plotted as Vo against [S]. For many single-substrate reactions, the data fits the Michaelis-Menten equation. This equation, named after Leonor Michaelis and Maud Menten, helps estimate the maximum velocity (Vmax) and the Michaelis constant (KM) for the enzyme being studied.

The Michaelis-Menten model is based on a few assumptions. No product is present at the start of the reaction. The rate of enzyme-substrate complex formation equals the rate of its breakdown into products and its dissociation. The enzyme concentration is minimal compared with the substrate concentration. The model also uses only the initial reaction rates. In this setup, the enzyme is either free or bound in an enzyme-substrate complex.

Scientists can also use other graph forms to analyze the same data. The Lineweaver-Burke plot, also called the double reciprocal plot, uses the reciprocal values from the Michaelis-Menten graph. On this plot, the y-intercept equals 1/Vmax and the x-intercept equals -1/KM. It is often used to estimate KM and Vmax and to visually distinguish competitive, non-competitive, and uncompetitive inhibitors.

Other rearrangements of the Michaelis-Menten equation include the Eadie-Hofstee plot and the Hanes-Woolf plot. These graphs are also used to determine kinetic parameters. Together, these methods help scientists compare reaction behavior and understand how enzymes respond to substrate concentration and inhibitors.

Graphing Enzyme Kinetics Data

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introduction to enzyme kinetics

Enzyme kinetics uses graphs to show how fast a biochemical reaction happens. Scientists measure the initial reaction rate, or velocity (Vo), at different substrate concentrations ([S]). They may also run trials with inhibitors or other molecules that change the reaction rate. The results are often plotted as Vo against [S]. For many single-substrate reactions, the data fits the Michaelis-Menten equation. This equation, named after Leonor Michaelis and Maud Menten, helps estimate the maximum...

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key terms and concepts

Learn how enzyme kinetics data is graphed with Michaelis-Menten, Lineweaver-Burke, Eadie-Hofstee, and Hanes-Woolf plots to estimate Vmax and KM.

Graphing Enzyme Kinetics Data | JoVE K12

cell biology

JoVE Core Cell Biology illustrates complex cellular processes in easy-to-understand yet comprehensive animated video lessons. This collection focuses on the essential components and functions of cells, including organelles and membranes, cellular transport, and cell energetics. It is complemented by scientist-in-action videos that demonstrate the application of cell biology in real-world research experiments.

Virginia  Standards of Learning

HIgh School

BIO.2

BIO.2.c

Chemistry

CH.7

CH.7.f

Florida Department of Education

High School

Life Science

SC.912.L.18

SC.912.L.18.4

SC.912.L.18.11

Texas Essential Knowledge and Skills

BIO.11

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Ribozymes

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Graphing Enzyme Kinetics Data

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