Citrullene is a special amino acid that is used in the urea cycle and as a precursor for synthesis of the amino acid Arg in the body. In which category would you place citrullene? Explain

Why is rubisco likely to be the most abundant protein in nature?

A seven-residue peptide was found to have an amino acid composition including glu, val, Lys, met, leu, and trp (there is more than one copy of one amino acid). Several reactions on samples of the peptide resulted in the following: a) Trypsin has no effect on the heptapeptide. b) If one cycle of Edman degradation provides the PTH derivative shown below, what does this tell you about the oligopeptide under investigation? [image] c) Chymotrypsin treatment yields a dipeptide, a tetrapeptide, and a free amino acid. Possibilities? d) The tetrapeptide contains val, lys, and met (only). What information does this give you? e)  Cyanogen bromide treatment generates a dipeptide, a tetrapeptide, and free Lys. f)What is the sequence of the peptide?

The hexokinases are a class of enzymes that catalyze the ATP-dependent phosphorylation of hexoses (sugars with six carbons). The hexokinases will bind only D-hexose sugars and not their L-counterparts. In general terms, describe the features of enzyme structure that make this specificity possible.