Activation Effects of Carnosine- and Histidine-Containing Dipeptides on Human Carbonic Anhydrases: A Comprehensive Study

Abstract

l-Carnosine (β-Ala-l-His) and several other histidine-containing peptides, including two N-methylated forms on the imidazole ring (l-anserine and l-balenine), two derivatives modified on the carboxyl function (carcinine and l-carnosinamide), two analogues differing in the length of the N-terminal residue (l-homocarnosine and Gly-l-His) and the N-acetyl derivatives, were investigated as activators of four isoforms of the metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1). The four human isoforms hCA I, II, VA and IX were activated in the low to high micromolar range, with a rather complex structure activity relationship. A performed computational study allowed us to rationalize these results and to propose a binding mode of these activators within the enzyme active site. Similarly to other CA activators, the here studied peptides could find relevant pharmacological applications such as in the management of CA deficiencies, for therapy memory and enhancing cognition or for artificial tissues engineering.

Coumarin carbonic anhydrase inhibitors from natural sources

“…These modulators of CA activity do not abolish but enhance the catalytic efficiency of these enzymes, which are already highly effective catalysts for the CO 2 hydration reaction 12,14,46 . The CA activators incorporate proton-shuttling moieties (PSMs) in their molecules, which most of the time are of the amino, carboxylate, or imidazole type [57][58][59][60] and bind at the entrance of the active site cavity. Thus, the activator binding site is superimposable with the coumarin-binding site shown in Figure 2(C) [57][58][59][60] .…”

A Simple Yet Multifaceted Enzyme

“…EZn 2+  HO -+ AH + (1) enzyme -activator complexes The activator binds within the enzyme active site with the formation of enzymeactivator complexes in which the activator molecule (which incorporates a proton shuttling moiety, PSM, Figure 1E) participates to the rate-determining step of the catalytic cycle, i.e., transfer of protons from the zinc-coordinated water to the external reaction medium, similar to the natural proton shuttle, which is residue His64 (in many CA isoforms) [-3]. In such enzyme-activator complexes, the proton transfer becomes intramolecular, being more efficient compared to the intermolecular transfer to buffer molecules, not bound within the enzyme cavity [81][82][83][84]. Many X-ray crystal structures with amines and amino acid activators were reported, among which histamine, L-and D-His bound to hCA II and hCA I, L-and D-Phe, D-Trp and L-adrenaline bound to hCA II, which confirmed this general CA activation mechanism [79][80][81][82][83][84].…”

“…In such enzyme-activator complexes, the proton transfer becomes intramolecular, being more efficient compared to the intermolecular transfer to buffer molecules, not bound within the enzyme cavity [81][82][83][84]. Many X-ray crystal structures with amines and amino acid activators were reported, among which histamine, L-and D-His bound to hCA II and hCA I, L-and D-Phe, D-Trp and L-adrenaline bound to hCA II, which confirmed this general CA activation mechanism [79][80][81][82][83][84]. The thirteen catalytically active mammalian CAs, (e.g., CA I-VA, VB, VI, VII, IX, XII-XV) were investigated for their interaction with a library of amino acids and amines.…”

“…It is worth mentioning that CA targeted drug design studies on CAAs are in their infancy: most of the known activators were identified by screening libraries of amines and amino acids followed eventually by the subsequent derivatization of such compounds (e.g., histamine, histidine, etc.) [80][81][82][83][84]. Administration of CAAs (such as D-Phe) to animal models of various diseases, was shown to lead to enhanced discrimination learning [85].…”

Synthesis and carbonic anhydrase activating properties of a series of 2-amino-imidazolines structurally related to clonidine1

“…where v 0 represents the initial velocity of the enzyme-catalysed reaction in the absence of activator [33][34][35][36][37][38][39] . This type of approach to measure enzyme-ligand interactions is in excellent agreement with recent results from native mass spectrometry measurements 40 .…”