the aldolase active site is LEAST likely to contain which amino acid?A.GluB.LysC.HisD.Arg

To determine which amino acid is least likely to be found in the active site of aldolase, it is important to consider the functional roles of each amino acid mentioned. The active site of enzymes is typically located in a region that facilitates substrate binding and catalysis.

1. Understanding the Amino Acids:

   • Glu (Glutamic acid): This is a negatively charged amino acid that can act as a proton donor, making it likely to be involved in chemical reactions within the active site.
   • Lys (Lysine): This is a positively charged amino acid that also plays a role in substrate binding and catalysis.
   • His (Histidine): This amino acid can act as both a proton donor and acceptor due to its side chain, which can be positively charged at physiological pH. This property makes it common in active sites.
   • Arg (Arginine): This is also a positively charged amino acid, often participating in enzyme-substrate interactions.

2. Analysis of Likelihood:

   • The active site of aldolase is involved in the catalysis of reactions that often require proton transfers or the stabilization of transition states. Amino acids that can either donate or accept protons are generally favored.
   • While Glu, Lys, and His have roles as proton donors or acceptors, contributing to the catalytic mechanism, Arg, while positively charged, is less involved in direct proton transfer due to its longer side chain and the stability of its guanidinium group.

3. Conclusion: Given the roles and properties of each amino acid, the one least likely to be present in the active site is likely:

Final Answer

D. Arg