[klp2332]

Just two questions,

1. All different kinds of enzymes have a specific charge, right?

2. When the Isoelectric point of an enzyme is at 0, this is at its optimum for enzyme activity?


Thanks

[shelanachium]

Most enzymes contain amino-acids which are basic or acidic (arginine - most basic, lysine, histidine (least basic); aspartic and glutamic acids (acidic)). At any given pH some of the basic ones will carry a positive charge, and the acidic ones a negative charge. In very alkaline solutions (high pH) all the acidic ones will have a negative charge and the basic ones will be neutral - though arginine is very basic indeed and needs pH13 or more to become neutral. At very low pH all the basic amino-acids will be positively charged whilst the acidic ones will be neutral ([-CO2]- groups protonate to neutral -CO2H groups in strongly acidic solutions)

The isoelectric point is the pH at which the total positive and negative charges are the same, so the molecule is overall neutral. The isoelectric point will tend to be at low pH if there is a predominance of acidic amino-acids and at high pH if basic ones predominate.

The isoelectric point is not necessarily where the enzyme is most active. It may need to carry a net charge to carry out its function.

[klp2332]

thank you,

you were really helpful