Q60.Given below are two statements :
Statement I :
In non-competitive type of enzymatic inhibition, the Vmax decreases and km remains unchanged.
Statement II :
Temperature below freezing point causes inactivation of enzymes.
In the light of the above statements, choose the most appropriate answer from the options given below :
(1) Both Statement I and Statement II are correct
(2) Both Statement I and Statement II are incorrect
(3) Statement I is correct but Statement II is incorrect
(4) Statement I is incorrect but Statement II is correct
Both Statement I and Statement II are correct, so option (1) is the right answer.
Non-Competitive Inhibition Effects
In non-competitive enzyme inhibition, inhibitors bind to an allosteric site on the enzyme or enzyme-substrate complex, reducing catalytic efficiency regardless of substrate concentration. This decreases Vmax (maximum velocity) by lowering effective enzyme concentration, while Km (Michaelis constant) remains unchanged as substrate affinity is unaffected.
Temperature Impact on Enzymes
Temperatures below freezing point (0°C) cause water to form ice crystals, disrupting enzyme structure through denaturation or inactivation, often halting activity until thawing. Enzymes lose conformational integrity, breaking hydrogen bonds critical for active sites.
Option Analysis
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Option 1: Correct—Statement I matches non-competitive kinetics (Vmax ↓, Km unchanged); Statement II holds as freezing disrupts enzymes.
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Option 2: Incorrect—both statements align with standard biochemistry principles.
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Option 3: Incorrect—Statement II is true; freezing inactivates enzymes via structural damage.
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Option 4: Incorrect—Statement I precisely describes non-competitive inhibition effects.
Introduction to Non-Competitive Inhibition Vmax Km Temperature Freezing Enzymes
Non-competitive inhibition vmax km temperature freezing enzymes covers key enzyme kinetics for exams like NEET. Statement I notes Vmax decreases with Km unchanged in non-competitive inhibition; Statement II states freezing temperatures inactivate enzymes. This analysis verifies both, breaks down options, and explains mechanisms.
Non-Competitive Inhibition Mechanics
Non-competitive inhibitors bind allosteric sites on E or ES, reducing turnover without competing for substrate, so Vmax falls but Km stays constant. Lineweaver-Burk plots show parallel lines with increased y-intercept (1/Vmax ↑). Unlike competitive (Km ↑, Vmax same), this is irreversible by excess substrate.
Freezing Effects on Enzymes
Below freezing, ice formation excludes solutes, concentrating salts that denature enzymes; H-bonds break, inactivating active sites. Many enzymes irreversibly lose activity post-thaw, though cryoprotectants like glycerol mitigate this in labs.
Statement Evaluation
Statement I correctly describes non-competitive effects: Vmax ↓, Km unchanged. Statement II is accurate—freezing causes inactivation via physical/chemical stress. Thus, option (1) both correct.
Exam Options Breakdown
Biological Relevance
These concepts underpin drug design (non-competitive inhibitors) and biotech (enzyme storage). Master non-competitive inhibition vmax km temperature freezing enzymes for CSIR-NET success.
