Question

#70 & 74

Page < 3 > 0f 4 0 - leucine the-Leu. ds. 18.70 Which would you expect to be more soluble in water, a peptide rich in alanine and leucine, or a peptide rich in lysine and aspartate? Explain. 18.71 Proteins are usually less soluble in water at their isoelec- tric points. Explain familiar nctional min from alyst ? e glycyl. Applications 18.72 (a) Tyramine is said to be the "decarboxylation" product of the amino acid tyrosine. Write the reaction and explain what is meant by "decarboxylation." (b) Phenelzine inhibits the deamination" of tyramine. What key characteristic of phenelzine makes it similar enough to tyramine that it is able to block deamination of tyramine? [Nutrition in Health and Disease, p. 5601 18.73 Why is it more important to have a daily source of protein than a daily source of fat or carbohydrates? [ Proteins in the Diet, p. 5691 18.74 What is an incomplete protein? (Proteins in the Diet, p. 569] 18.75 In general, which is more likely to contain a complete (balanced) protein for human use--food from plant sources or food from animal sources? Explain. Proteins in the Diet, p. 569] 18.76 Two of the most complete (balanced) proteins (that is proteins that have the best ratio of the amino acids for humans) are cow's milk protein (casein) and egg white protein. Explain why (not surprisingly) these are very balanced proteins for human growth and development. [Proteins in the Diet, p. 569) 18.77 The proteins collagen, bovine insulin, and human hemo globin have isoelectric points of 66, 5.4, and 7.1, respec tively. Suppose a sample containing these proteins is applied to an electrophoresis strip in a buffer at pH 6.6. Describe the motion of each with respect to the positive and negative electrodes in the electrophoresis apparatus Irati Analisis by Electroforesis, p. 573 -co- tion. This formula ds. What ide no acids - obtained pH

Answer 1

#70.Peptide rich in lysine and aspartate will be more soluble in water because their side chain contains polar functional groups such as NH2 and COO-, whereas alanine and leucine has hydrocarbon side chains which are hydrophobic in nature hense less soluble.

#74. Proteins which doesn't contain all the nine essential amino acids ( histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine) which are essential for our body are called incomplete protein. Such as beans and peas.