Carboxypeptidase Y (CPY) contains ten cysteine residues that form five disulfide bonds in the native structure of CPY. Suppose CPY is reduced and unfolded in urea.Part AIf the reduced unfolded protein were oxidized prior to the removal of the urea, what fraction of the resulting mixture would you expect to possess native disulfide bonds?Express your answer using three significant figures.

Bovine pancreatic trypsin inhibitor (BPTI; as shown) contains six cysteine residues that form three disulfide bonds in the native structure of BPTI. Suppose BPTI is reduced and unfolded in urea (as illustrated for RNase A as shown). If the reduced unfolded protein were oxidized prior to the removal of the urea, what fraction of the resulting mixture would you expect to possess native disulfide bonds?

D-Talose is a C2 epimer of D-galactose. Using the Fischer projection structure, draw the product of reaction ofD-talose with the given reagent or enzyme and write the systematic name of the product.  1. 2,4-DNP 2. Reaction with aminotransferase and then acetyltransferase at C4

With aldoses, upon biosynthesis, uranic acid is formed. But can biosynthesis happen with ketoses, for example with fructose? In that case, will both terminal OH's on the Fischer projections be converted to COOH?

Carboxypeptidase, which sequentially removes carboxyl-terminal amino acid residues from its peptide substrates, is a single polypeptide of 307 amino acids. The two essential catalytic groups in the active site arefurnished by Arg 145 and Glu 270 .(a) If the carboxypeptidase chain were a perfect α helix, how far apart (in Å) would Arg 145 and Glu 270 be? (b) Explain how the two amino acid residues can catalyze a reaction occurring in the space of a few angstroms

The following table shows the molecular masses (Mr) and isoelectric points (pI) of five proteins: Protein Mr pI Chicken egg white lysozyme 14,000 11.0 Carbonic anhydrase 30,000 5.4 Ovalbumin 45,000 4.5 Phosphorylase b 97,000 6.7 Lactate dehydrogenase 140,000 7.12 (a) A solution containing these five proteins was adjusted to pH 7.0 and then applied to a SIZE-EXCLUSION COLUMN. Assume that these five protein molecules are spherical in shape. Which protein is likely to be eluted LAST from the column? Explain briefly.  (b) In another experiment, this protein mixture was first adjusted to pH 6.7 before applying to a CATION-EXCHANGE COLUMN.  (i)What is the net charge on phosphorylase b? (ii) Which of these five proteins will bind to the CATION-EXCHANGER? Explain briefly.v

Is a protein as good a cellular buffer at physiological pH as its constituent amino acids would be if they were present as free amino acids in proportional concentrations in the cell? Explain Based on your rationale in the previous question, describe the difference in the dissociation constants of the α-COOH of GABA and glutamate, and the differences in the dissociation constants of the amino group in each of these amino acids.

Histidine is frequently used as a general acid or base in enzyme catalysis. Considering the pKa value of the side chain, suggest a reason why is this so?

Based on your knowledge of the natural amino acids, what would you expect pKa of the sidechain of beta-(aminomethyl)succinic acid to be? Draw an appropriate titration curve for beta-(aminomethyl)succinic acid, labeling the axes, indicating the equivalence points and the pKavalues, and use a drawing to show the protonated/deprotonated forms.

Determine the pI of the peptide H2N-Ala-Lys-Ser-Arg-COOH at pH 11, please explain why some pKas are used in the solution of the problem while others are not.