Question

Which of the following statements is NOT correct?

A. Glycoproteins can have the carbohydrates in either O-glycosidic bonds to Ser or Thr residues or in N-glycosidic bonds to Lys residues.

B. Glycosylated proteins are generally either extracellular proteins or membrane proteins with the carbohydrate residues on the extracellular side of the membrane.

C. Penicillin is a mechanism-based inhibitor of a transpeptidase required for bacterial cell wall synthesis.

D. Proteoglycans are composed of core proteins with one or more attached glycosaminoglycans.

E. The ABO blood group antigens are determined by oligosaccharides that are part of either glycosphingolipids or membrane glycoproteins on the outer surface of the cell membrane.

Answer 1

Glycosylated proteins are generally either extracellular proteins or membrane proteins with the carbohydrate residues on the extracellular side of the membrane.
Penicillin is a mechanism-based inhibitor of a transpeptidase required for bacterial cell wall synthesis.
Proteoglycans are composed of core proteins with one or more attached glycosaminoglycans.
The ABO blood group antigens are determined by oligosaccharides that are part of either glycosphingolipids or membrane glycoproteins on the outer surface of the cell membrane.
The statements given in options, "B, C,D and E" are the correct statements.
Hence, options, "B, C,D and E" are the wrong answers.

In glycoproteins, sugars are attached either to the amide nitrogen atom in the side chain of asparagine (which istermed an N-linkage) or to the oxygen atom in the side chain of serine or threonine (termed an O-linkage).
Thus, the statement, given in option, "A" is the wrong statement.
Hence, option, "A" is the correct answer.