Hydrolysis of a thiopeptide by cadmium carboxypeptidase A

A thiono-β-lactam substrate for the β-lactamase II of Bacillus cereus. Evidence for direct interaction between the essential metal ion and substrate

“…Thus the preference of the metalloenzyme for the thiono substrate with respect to the oxo compound increases in this order. Setting aside the question of Co2+ for a moment, the order Mn2+ < Zn'+ < Cd2+ is also the order of increasing thiophilicity of these metal ions [17,26,27], and the correlation between this and the order of catalytic preference for compound (Tb) is striking and can be interpreted [14,17] as evidence for kinetically significant direct contact between the active-site metal ion of fl-lactamase IT and the /J-lactam carbonyl heteroatom.…”

“…One approach to the answer of the above-mentioned question that has apparently yielded an unambiguous, or at least an unchallenged, conclusion comes from employment of thioamides and metalloenzymes containing active-site metal ions of distinctly different thiophilicity. Although thiopeptides are generally poorer substrates, of carboxypeptidase A for example, than are the analogous peptides [14][15][16][17], they are much less poor, again relative to the peptides, when the active-site Zn2+ ion is replaced by a more thiophilic metal ion such as Cd2+ [14,17]. Conversely, a metal ion less thiophilic than Zn2+, such as Mn2", yields a relatively poorer thioamidase [17].…”

One-Atom Substitution Enables Direct and Continuous Monitoring of Histone Deacylase Activity

“…Metalloprotease carboxypeptidase A can hydrolyze thioxylated peptide bonds in dipeptide derivatives with slightly reduced k cat values. − Interestingly, activity against thioamide-containing substrates increased remarkably if the active site metal ion was substituted with more thiophilic cadmium or cobalt ions. , In contrast, aminopeptidase P can hydrolyze thioxylated peptide bonds with >1000-fold reduced k cat values . Additionally, leucine aminopeptidase cannot hydrolyze thioxylated amide bonds, but such peptide derivatives represent good competitive inhibitors, showing that these compounds bind in a similar manner to the active site like the respective substrates.…”

Synthesis, X‐ray crystallographic structures of thio substituted N‐acetyl N′‐methylamide alanine and evaluation of sp2 sulfur parameters of the CFF91 force field

“…In particular, the use of non‐natural amino acids that restrict the molecular conformations allows more predictable peptide conformers to be constructed with potentially increased binding affinity to proteins (3–7). Furthermore, non‐natural amino acids have been used for de novo design (3,8–12), to confer resistance to enzymatic degradation within the body (2,13,14), to probe the function of protein structure (15–17), to design peptide conformers displaying novel fold or secondary structure (18,19) and to create new combinatorial chemistry libraries (20–25). While the greater bulk of the sulfur atom is expected to restrict the conformational freedom of peptide chains on going from an amide bond to a thioamide bond, the structural ramifications of such substitutions are not yet fully understood.…”