Three-Dimensional Molecular Modeling of a Diverse Range of SC Clan Serine Proteases

From bitter to delicious: properties and uses of microbial aminopeptidases

Protein hydrolysates are easily digested and utilized by humans and animals, and are less likely to cause allergies. Protein hydrolysis caused by endopeptidases often leads to the exposure of hydrophobic amino acids at the ends of peptides, which consequently causes bitter taste. Microbial aminopeptidases remove the exposed hydrophobic amino acids at the ends of aminopeptides, which improves taste, allowing for easier production. This processe is attacking significant attention from industry and laboratories. Aminopeptidases selectively hydrolyze peptide bonds from the N-terminal of proteins or peptides to produce free amino acids. Aminopeptidases can be classified into leucine, lysine, methionine and proline aminopeptidases by hydrolyzed N-terminal residues; metallo-, serine- and cysteine- aminopeptidases by the reaction mechanisms; dipeptide and triphoptide enzymes by the released number of amino acid residues at the end of hydrolyzed peptides; or acidic, neutral and basic aminopeptidases by their optimal hydrolysis pH. Commercial aminopeptidases are generally produced by microbial fermentation, and are mainly applied in the debittering of protein hydrolysates, the deep hydrolysis of protein, and the production of condiments, cheese, and bioactive peptides, as well as for disease detection in the medical industry.

Purification and Biochemical Characterization of a Novel Thermostable Serine Protease from Geobacillus sp. GS53

Proteases account for approximately 60% of the enzyme market in the world, and they are used in various industrial applications including the detergent industry. In this study, production and characterization of a novel serine protease of thermophilic Geobacillus sp. GS53 from Balçova geothermal region, İzmir, Turkey, were performed. The thermostable protease was purified through ammonium sulfate precipitation and anion-exchange chromatography. The results showed that the protease had 137.8 U mg^-1 of specific activity and optimally worked at 55 ^oC and pH 8. It was also active in a broad pH (4-10) and temperature (25-75 °C) ranges. The protease was highly stable at 85 °C and demonstrated relative stability at pH 4, 7, and 10. Also, the enzyme had high stability against organic solvents and surfactants; enzyme relative activity did not decrease below 81% upon preincubation for 10 min. Ca²⁺, Cu²⁺, and Zn²⁺ ions slightly induced protease activity. The protease was highly specific to casein, skim milk, Hammerstein casein, and BSA substrates. These results revealed that the protease might have a potential effect in a variety of industrial fields, especially the detergent industry, because of its high thermostability and stability to surfactants.

A systematic reconsideration on proteases

Proteases are a group of large complex enzyme molecules that perform highly focused proteolysis functions. A vast quantity of the protease enzymes is predominantly sourced from microbial fermentation process, although proteases tend to natively present in plant, animals and humans. Proteases possess a pervasive importance in medical and pharmaceutical sector, because of its enriched specificity towards biomolecules. They are also actively encompassed in regulating certain physiological pathways. A distinct territory of human disorders is treated by substrate specific proteases. Enormous numbers of catalytic activities in habitual metabolism process of a living organism are protease dependent. Pilot scale researches and product development in industrial biotechnology sectors are wholly based on any one of the protease enzymes. The applications of the protease enzymes and its economic benefits of being an eco-friendly material are far-reaching. This review presents a brief overview on the classification and sources of various types of proteases. We describe the essential evidences of role of protease in different sectors. The proteases could be a potential relieves to harmful synthetic chemicals in distinctive industrial processes and thus gains global perception.

Structure Determination of Mycobacterium tuberculosis Serine Protease Hip1 (Rv2224c)

The Mycobacterium tuberculosis (Mtb) serine protease Hip1 (hydrolase important for pathogenesis; Rv2224c) promotes tuberculosis (TB) pathogenesis by impairing host immune responses through proteolysis of a protein substrate, Mtb GroEL2. The cell surface localization of Hip1 and its immunomodulatory functions make Hip1 a good drug target for new adjunctive immune therapies for TB. Here, we report the crystal structure of Hip1 to a resolution of 2.6 Å and the kinetic studies of the enzyme against model substrates and the protein GroEL2. The structure shows a two-domain protein, one of which contains the catalytic residues that are the signature of a serine protease. Surprisingly, a threonine is located within the active site close enough to hydrogen bond with the catalytic residues Asp463 and His490. Mutation of this residue, Thr466, to alanine established its importance for function. Our studies provide insights into the structure of a member of a novel family of proteases. Knowledge of the Hip1 structure will aid in designing inhibitors that could block Hip1 activity.

Molecular characterization of alkaline protease of Bacillus amyloliquefaciens SP1 involved in biocontrol of Fusarium oxysporum

An alkaline protease gene was amplified from genomic DNA of Bacillus amyloliquefaciens SP1 which was involved in effective biocontrol of Fusarium oxysporum. We investigated the antagonistic capacity of protease of B. amyloliquifaciens SP1, under in vitro conditions. The 5.62 fold purified enzyme with specific activity of 607.69U/mg reported 24.14% growth inhibition of F. oxysporum. However, no antagonistic activity was found after addition of protease inhibitor i.e. PMSF (15mM) to purified enzyme. An 1149bp nucleotide sequence of protease gene encoded 382 amino acids of 43kDa and calculated isoelectric point of 9.29. Analysis of deduced amino acid sequence revealed high homology (86%) with subtilisin E of Bacillus subtilis. The B. amyloliquefaciens SP1 protease gene was expressed in Escherichiax coli BL21. The expressed protease was secreted into culture medium by E. coli and exhibited optimum activity at pH8.0 and 60°C. The most reliable three dimensional structure of alkaline protease was determined using Phyre 2 server which was validated on the basis of Ramachandran plot and ERRAT value. The expression and structure prediction of the enzyme offers potential value for commercial application in agriculture and industry.

Genus-Wide Comparative Genome Analyses of Colletotrichum Species Reveal Specific Gene Family Losses and Gains during Adaptation to Specific Infection Lifestyles

Members from Colletotrichum genus adopt a diverse range of lifestyles during infection of plants and represent a group of agriculturally devastating pathogens. In this study, we present the draft genome of Colletotrichum incanum from the spaethianum clade of Colletotrichum and the comparative analyses with five other Colletotrichum species from distinct lineages. We show that the C. incanum strain, originally isolated from Japanese daikon radish, is able to infect both eudicot plants, such as certain ecotypes of the eudicot Arabidopsis, and monocot plants, such as lily. Being closely related to Colletotrichum species both in the graminicola clade, whose members are restricted strictly to monocot hosts, and to the destructivum clade, whose members are mostly associated with dicot infections, C. incanum provides an interesting model system for comparative genomics to study how fungal pathogens adapt to monocot and dicot hosts. Genus-wide comparative genome analyses reveal that Colletotrichum species have tailored profiles of their carbohydrate-degrading enzymes according to their infection lifestyles. In addition, we show evidence that positive selection acting on secreted and nuclear localized proteins that are highly conserved may be important in adaptation to specific hosts or ecological niches.