One mRNA codon for the amino acid Gln is CAA. A mutation could alter this codon from CAA to UAA. UAA is a STOP codon. State what is meant by a STOP codon.
Many proteins containing the amino acids shown in Fig. 4.1 are globular. Describe how the three R groups in Fig. 4.1 may help produce a protein's globular structure.
An example of a globular protein is the enzyme starch phosphorylase. It catalyses the conversion of starch to glucose-1-phosphate. Name the type of bond that is broken when starch is converted to glucose-1-phosphate.
With reference to Fig. 4.2, compare the enzyme activity when it is free in solution with the activity when it is immobilised.
State how the Michaelis-Menten constant ($K_m$) is obtained from $V_{max}$ for an enzyme.
The $K_m$ values for starch phosphorylase were found both when the enzyme was free in solution and when it was immobilised. The values were: free in solution, $K_m = 0.34\,\text{mmol dm}^{-3}$; immobilised, $K_m = 0.84\,\text{mmol dm}^{-3}$. Suggest why the two values are different.