Engineering multi-functional protein biologics through PAL-mediated hydrazide ligation

Attributed to the -effects, hydrazides are nucleophilic despite being non-basic. Herein, we report that the hydrazide nucleophiles are effective acyl acceptors in the ligation reactions catalyzed by peptidyl asparaginyl ligases (PALs). Because hydrazides are easily functionalizable, hydrazide ligation is highly versatile. Interestingly, the linkages formed with the hydrazide substrates have varying degrees of liability toward the PAL enzyme, with some being remarkably resistant and thus ensuring nearly irreversible ligation. Using the hydrazide ligation method, we labelled an EGFR-targeting affibody-Fc fusion protein with various functional moieties to generate selective and potent cancer-imaging and therapeutic agents. Irreversible hydrazide ligation also allowed a sequential ligation scheme to be conducted on a protein. Using this scheme, quadruple FITC labels were introduced onto the N- and C-termini of the affibody-Fc protein to yield a bi-specific engager for Car-NK cell therapy. Our work expands the substrate scope of PAL enzymes and further point to their promise as a precision manufacturing tool for multi-functional protein biologics.

Candida antarctica lipase B-catalyzed regioselective deacylation of dihydroxybenzenes acylated at both phenolic hydroxy groups

Candida antarctica lipase B proved to be highly active in the deacylation of substituted hydroquinones and resorcinols acylated at both phenolic hydroxy groups. The deacylation reactions were much faster than the corresponding direct acylations of these dihydroxybenzenes catalyzed by the same lipase. More importantly, they took place generally in a markedly regioselective manner: the acyloxy group remote from the substituent was preferentially cleaved. The main or exclusive products obtained were the regioisomers of those produced through the direct acylation of the dihydroxybenzenes. In the case of alkyl-substituted hydroquinone derivatives, the regioselectivity increased with an increase in the bulk of the substituent. In the case of 4-substituted diacylated resorcinols, the 3-O-monoacyl derivatives were obtained generally as the sole products. Quite interestingly, some secondary alcohols proved to act as better acyl acceptors than the corresponding primary alcohols in these enzymatic deacylations.

One-Pot Synthesis of Diverse dl-Configuration Dipeptides by a Streptomyces d-Stereospecific Amidohydrolase

ABSTRACTThe synthesis of diversedl-configuration dipeptides in a one-pot reaction was demonstrated by using a function of the aminolysis reaction of ad-stereospecific amidohydrolase fromStreptomycessp., a clan SE, S12 family peptidase categorized as a peptidase withd-stereospecificity. The enzyme was able to use various aminoacyl derivatives, includingl-aminoacyl derivatives, as acyl donors and acceptors. Investigations of the specificity of the peptide synthetic activity revealed that the enzyme preferentially usedd-aminoacyl derivatives as acyl donors. In contrast,l-amino acids and their derivatives were preferentially used as acyl acceptors. Consequently, the synthesized dipeptides had adl-configuration whend- andl-aminoacyl derivatives were mixed in a one-pot reaction. This report also describes that the enzyme produced cyclo(d–Pro-l-Arg), a specific inhibitor of family 18 chitinase, with a conversion rate ford-Pro benzyl ester andl-Arg methyl ester to cyclo(d-Pro–l-Arg) of greater than 65%. Furthermore, based on results of cyclo(d-Pro–l-Arg) synthesis, we propose a reaction mechanism for cyclo(d-Pro–l-Arg) production.

Prolyl Aminopeptidase from Streptomyces thermoluteus subsp. fuscus Strain NBRC14270 and Synthesis of Proline-Containing Peptides by Its S144C Variant

ABSTRACT We specifically examined an exopeptidase, prolyl aminopeptidase (PAP), as a target for synthesis of proline-containing peptides. A PAP from Streptomyces thermoluteus subsp. fuscus NBRC14270 (PAP14270) was obtained using sequence-based screening. From PAP14270, 144Ser was replaced by Cys (scPAP14270) to give aminolysis activity. In contrast to wild-type PAP14270, scPAP14270 produced a polymer of proline benzyl ester and cyclo[Pro-Pro]. The product mass was confirmed using liquid chromatography-mass spectrometry (LC/MS). Several factors affecting the reaction, such as the pH, concentration of the substrate, and reaction time, were measured to determine their effects. Furthermore, a correlation was found between substrate specificity in proline peptide synthesis and the log D value of acyl acceptors in aminolysis catalyzed by scPAP14270. Results showed that dipeptide synthesis proceeded in a weakly acidic environment and that cyclization and polymerization occurred under alkaline conditions. Furthermore, results suggest that almost all amino acid esters whose log D value is greater than 0, except hydroxyproline benzyl ester (Hyp-OBzl), can be recognized as acyl acceptors. These findings support the use of PAPs as a tool for production of physiologically active proline peptides.

Lipases as biocatalysts for biodiesel production

Lipases can be used for a variety of biotechnological applications: synthesis of fine chemicals, therapeutics, agrochemicals, cosmetics, flavors, biopolymers and biodiesel. Biodiesel is an alternative fuel for diesel engines that is environmentally acceptable. Conventionally, biodiesel is produced by transesterification of triglycerides and short chain alcohols in the presence of an acid or an alkaline catalyst. There are several problems associated with this kind of production that can be resolved by using lipase as the biocatalyst. The usage of lipases has several advantages over the conventional chemical methods. It is considered as less energy intensive and environmentally friendly. However, there are two main obstacles associated with the effective utilization of lipases in the production of biodiesel. The main one is the cost of the enzyme and its poor stability in the presence of excess alcohol. Several strategies are proposed to overcome these drawbacks: immobilization of lipases, stepwise addition of alcohol, and the usage of novel acyl acceptors and the usage of whole cell biocatalysts.