How many stereoisomers are possible for: CH,-CH-CH-C-CH-CH, ОН ОН ОН ОН ОН

9L.9

The anabolic steroid methandrostenolone is shown here. (a) How does it diff er structurally from testosterone? (b) Why might such drugs be administered to burn victims?

The amino acid arginine ionizes according to the following scheme: NH, NH2 NH2 H NH, C=N C=N C=N C=N-H pk = 2.17 -H pK. = 8.99 -H pK = 125 -H* H. NH NH NH NH H (CH,)a H (CH), +H* (CH)a (CH,)a H,N-C-coo- +H* +H* H-N*-C-COOH H-N-C-Co- H,N-C-co- H. нн H. H II II IV (a) Calculate the isoelectric point of arginine. You can neglect contributions from form I. Why? (b) Calculate the average charge on arginine when pH = 9.20. (Hìnt: Find the average charge for each ionizable group and sum these together.) (c) Is the value of average charge you calculated in part b reasonable, given the pl you calculated in part a? Explain your answer.