Design and Synthesis of Sugar‐Responsive Semiartificial Myoglobin Triggered by Modulation of Apoprotein–Cofactor Interactions

Abstract

Phenylboronic acid groups as sugar recognition sites were successfully introduced into native myoglobin by a cofactor-reconstitution method. Spectrophotometric pH titration demonstrated the sugar-induced pK, shift of the H,O coordinated to the heme center of the semisynthetic myoglobin bearing phenylboronic acids (met-Mb(PhBOH),). By means of circular dichroism (CD) and paramagnetic 'H NMR spectroscopies, it was provcn that sugars that were bound to phenylboronic acid sites induced the rearrangement of the heme crevice to reinforce the heme cofactor-apoprotein interactions. The structural changes that were induced by the binding o f sugars subsequently enhanced the dioxygen storage activity of Mb(PhBOH), . Such sugarinduced structural and functional changes did not occur for other modified Mbs that

Peroxidase Activity of Myoglobin Is Enhanced by Chemical Mutation of Heme-Propionates

“…The p K a of the coordinated water molecule is slightly higher in rMb( 1 ) (p K a = 9.0) at 20 °C than that observed for nMb (p K a = 8.9). However, the deviation from the p K a in nMb is rather small compared with those values for a series of reconstituted Mbs reported in the literature 1 Scheme of chemically modified heme 1 and rMb( 1 ) (upper), and hypothetical structure of rMb( 1 ) based on Brayer's coordinate (lower) …”

Peptide and Protein Recognition by Designed Molecules

“…Modification of the functional groups on a protein has been utilized to allow a protein to adapt to a nonaqueous environment, or for stabilization of its tertiary conformation through metal-mediated cross-linking . The use of metals for the separation or modification of proteins has been proposed. , Similarly, proteins have been engineered through either cofactor reconstitution or semisynthesis to react to certain environmental factors. − This area of research is illustrated in recent work from Hamachi et al Here a semisynthetic ribonuclease S was designed to incorporate metal-chelated residues, on the basis of earlier work from Hopkins. , Synthetic ribonuclease C peptides incorporating one or two copies of the unnatural iminodiacetic acid amino acid (Ida) were synthesized. The researchers demonstrated that the activity of ribonuclease S‘ was related to the concentration of Cu(II), and they proposed a mechanism where two Ida molecules cooperatively bind one Cu(II) to stabilize the ribonuclease C helical conformation and thus activate the enzyme (Figure ).…”

Coupling a Natural Receptor Protein with an Artificial Receptor to Afford a Semisynthetic Fluorescent Biosensor

“…Molecular Design of Phenylboronic Acid-Appended ConA. We recently developed a new method (post-photoaffinity labeling modification: P-PALM) to incorporate a unique benzylthiol group proximal to the sugar-binding pocket of a natural lectin (Concanavalin A (ConA), an α-mannoside or α-glucoside binding protein, was used in this study). The benzylthiol was utilized as a reactive tag for fluorescent probes (Scheme ).…”