Biochemical properties and potential applications of recombinant leucine aminopeptidase from Bacillus kaustophilus CCRC 11223

Expression, Characterisation, Homology Modelling and Molecular Docking of a Novel M17 Family Leucyl-Aminopeptidase from Bacillus cereus CZ

Leucyl-aminopeptidase (LAP), an important metallopeptidase, hydrolyses amino acid residues from the N-terminus of polypeptides and proteins, acting preferentially on the peptide bond formed by N-terminus leucine. A new leucyl-aminopeptidase was found in Bacillus cereus CZ. Its gene (bclap) contained a 1485 bp ORF encoding 494 amino acids with a molecular weight of 54 kDa. The bcLAP protein was successfully expressed in E. coli BL21(DE3). Optimal activity is obtained at pH 9.0 and 58 °C. The bcLAP displays a moderate thermostability and an alkaline pH adaptation range. Enzymatic activity is dramatically enhanced by Ni2+. EDTA significantly inhibits the enzymatic activity, and bestatin and SDS also show strong inhibition. The three-dimensional model of bcLAP monomer and homohexamer is simulated byPHYRE2 server and SWISS-MODEL server. The docking of bestatin, Leu-Trp, Asp-Trp and Ala-Ala-Gly to bcLAP is performed using AutoDock4.2.5, respectively. Molecular docking results show that the residues Lys260, Asp265, Lys272, Asp283, Asp342, Glu344, Arg346, Gly372 and His437 are involved in the hydrogen bonding with the ligands and zinc ions. There may be two nucleophilic catalytic mechanisms in bcLAP, one involving His 437 or Arg346 and the other involving His437 and Arg346. The bcLAP can hydrolyse the peptide bonds in Leu-Trp, Asp-Trp and Ala-Ala-Gly.

Therapeutic and biotechnological applications of substrate specific microbial aminopeptidases

Aminopeptidases (EC 3.4.11.) belongs to exoprotease family, which can catalyze the cleavage of peptide bond which connects the N-terminal amino acid to the penultimate residue in a protein. Aminopeptidases catalyze the process of removal of the N-terminal amino acids of target substrates by sequential cleavage of one amino acid residue at a time. Microbial aminopeptidase are of great acceptance as industrial enzymes with varying applications in food and pharma industry since these enzymes possess unique characteristics than aminopeptidases from other sources. This review describes the various applications of microbial aminopeptidases in different industrial sectors. These enzymes are widely used in food industry as a debittering agent as well as in the preparation of protein hydrolysates. In baking, brewing, and cheese making aminopeptidases are extensively used for removing the bitterness of peptides. The inhibitors of these enzymes are found great clinical applications against various diseases such as cancer, diabetes, and viral infections. Aminopeptidases are widely used for the synthesis of biopeptides and amino acids, and found to be efficient than chemical synthesis. These enzymes are capable of hydrolyzing organophosphate compounds, thus having biological as well as environmental significance.

Key Points • Cleaves the amino-terminal amino acid residues from proteins and peptides. • Microbial aminopeptidase are of great acceptance as both therapeutic and industrial enzyme. • Review describes the potential applications of microbial aminopeptidases.

Exploring the influence of phospholipid monolayer conformation and environmental conditions on the interfacial binding of Gibberella Zeae lipase

The involvement of different parameters on Gibberella zeae lipase (GZEL) membrane binding were characterized by using monomolecular film technology and circular dichroism spectroscopy. Among four kinds of phospholipid monolayers, 1,2‑dimyristoyl‑sn‑glycero‑3‑phosphoethanolamine have the highest maximum insertion pressure (MIP) value. Comparing the GZEL adsorption to phosphatidylcholine monolayers with different acyl chains in sn-1 and sn-2 positions, the higher MIP values were found for 1,2‑dilauroyl‑sn‑glycero‑3‑phosphocholine. Significantly improvement between 1,2‑dioleoyl‑sn‑glycero‑3‑phosphocholine and 1,2‑distearoyl‑sn‑glycero‑3‑phosphocholine suggested that the presence of fatty acid unsaturation may affect protein adsorption by changing the chemical structure in each phospholipid. The MIP value was shown higher (48.6 mN m^-1) at pH 5 and pH 6 (47.5 ± 1.9 mN m^-1) but decreased significantly (34.2 mN m^-1) at pH 9. This may indicate that the proportion of helices in the protein decreases with the alteration of the catalytic center, thus affecting the binding of the protein to its substrate. The MIP values obviously decreased with increasing salt ion concentration, suggesting that excessive salt ion concentration may destabilize the secondary and tertiary structures of the protein, thereby affecting the characteristics of its adsorption at the interfaces. Present studies improve our understanding on the protein-membrane interaction of this enzyme.

High-level expression and characterization of the Bacillus subtilis subsp. subtilis str. BSP1 YwaD aminopeptidase in Pichia pastoris

Aminopeptidases are widely used for creating protein hydrolysates and peptide sequencing. The ywaD gene from a new Bacillus isolate, named Bacillus subtilis subsp. subtilis str. BSP1, was cloned into the yeast expression vector pHBM905A and expressed and secreted by Pichia pastoris strain GS115. The deduced amino acid sequence of the aminopeptidase encoded by the ywaD gene shared up to 98% identity with aminopeptidases from B. subtilis strains 168 and zj016. The yield (3.81 g/l) and specific activity (788 U/mg) of recombinant YwaD in high-density fermentation were extremely high. And 829.83 mg of the purified enzyme (4089.72 U/mg) were harvested. YwaD was glycosylated, and its activity decreased after deglycosylation, which was similar to that of the aminopeptidase from B. subtilis strain zj016. YwaD was most active toward l-arginine-4-nitroanilide. Moreover, it exhibited high resistance to carbamide, which was not true for aminopeptidases from B. subtilis strains 168 and zj016, which could simplify the purification of YwaD. Moreover, the expression and parts of characterization of the aminopeptidase from B. subtilis strain 168 in Pichia pastoris were added as supplementary material. The sequence and other characteristics of YwaD were compared with those of aminopeptidases from B. subtilis strains 168 and zj016, and they will provide a solid foundation for further research on the influence of amino acid mutations on the function of aminopeptidases.