Question

Optimum temperature and pH for enzyme.

• A. $20$-${25}^o$-C and $7$pH
• B. $20$-${35}^o$-C and $6.5$ pH
• C. $20$-${35}^o$-C and $7.5$pH
• D. All correct

Answer 1

The correct option is A $20$-${25}^o$-C and $7$pH

The optimum temp of enzymes is 20-35°C. They become inactivated at very low temperature and denatured (destroyed) at very high temp i.e. greater than 45°C. Low molecular weight enzymes are comparatively more heat stable. In archaebacterium Pyrococcus furiosus, the optimum temperature of hydrogenase is greater than 95°C. This heat-stable enzyme enables Pyrococcus to grow at 100°C. The optimum pH of most endoenzyme is pH 7.0 (neutral pH). However, digestive enzymes can function at different pH. For example, salivary amylase act best at pH 6.8, pepsin act best at pH2 etc. Any fluctuation in pH from the optimum causes ionization of R-groups of amino acids which decrease the enzyme activity. Sometimes a change in pH causes the reverse reaction, e.g. at pH 7.0 phosphorylase break down starch into glucose 1- phosphate while at pH5 the reverse reaction occurs.

So, the correct option is '20-25${}^o$ C and 7.0 pH'