Probing the Internal pH and Permeability of a Carboxysome Shell.

The carboxysome is a protein-based nanoscale organelle in cyanobacteria and many proteobacteria, which encapsulates the key CO-fixing enzymes ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and carbonic anhydrase (CA) within a polyhedral protein shell. The intrinsic self-assembly and architectural features of carboxysomes and the semipermeability of the protein shell provide the foundation for the accumulation of CO within carboxysomes and enhanced carboxylation. Here, we develop an approach to determine the interior pH conditions and inorganic carbon accumulation within an α-carboxysome shell derived from a chemoautotrophic proteobacterium and evaluate the shell permeability.

A Method for Detecting Antioxidant Activity of Antioxidants by Utilizing Oxidative Damage of Pigment Protein.

A simple and effective method for detecting the antioxidant activity by utilizing oxidative damage of pigment proteins was developed. In this method, phycocyanin and bovine hemoglobin pigment proteins were used as substrates attacked by free radicals; AAPH was used as a free radical initiator; and Trolox as a positive control; and the fermentation products of Lactobacillus plantarum 793, phycocyanin hydrolysates, salmon skin collagen hydrolysates, and synthetic peptides PMRGGYHY and FCVLRP are antioxidants inspected in this study. Because of being attacked by free radicals, the absorbance of the pigment proteins at their characteristic absorption peak changes with time.

Simultaneous preparation of antioxidant peptides and lipids from microalgae by pretreatment with bacterial proteases.

Chlorella can produce large amounts of lipids and therefore has great potential for biodiesel production. In this study, Chlorella protothecoides was hydrolyzed by several kinds of extracellular bacterial proteases produced by Pseudoalteromonas sp. ZB23-2, B27-3 and JS4-1 before lipid extraction.

Phylogenetic Distribution of Polysaccharide-Degrading Enzymes in Marine Bacteria.

Deconstruction is an essential step of conversion of polysaccharides, and polysaccharide-degrading enzymes play a key role in this process. Although there is recent progress in the identification of these enzymes, the diversity and phylogenetic distribution of these enzymes in marine microorganisms remain largely unknown, hindering our understanding of the ecological roles of marine microorganisms in the ocean carbon cycle. Here, we studied the phylogenetic distribution of nine types of polysaccharide-degrading enzymes in marine bacterial genomes.

Reprogramming bacterial protein organelles as a nanoreactor for hydrogen production.

Compartmentalization is a ubiquitous building principle in cells, which permits segregation of biological elements and reactions. The carboxysome is a specialized bacterial organelle that encapsulates enzymes into a virus-like protein shell and plays essential roles in photosynthetic carbon fixation. The naturally designed architecture, semi-permeability, and catalytic improvement of carboxysomes have inspired rational design and engineering of new nanomaterials to incorporate desired enzymes into the protein shell for enhanced catalytic performance.

New insights into the structure-activity relationships of antioxidative peptide PMRGGGGYHY.

The sequence and structure of antioxidant peptides play fundamental roles in their antioxidant functions. However, the structural mechanism of antioxidant peptides is still unclear. In this study, we used quantum calculations to reveal the antioxidant mechanism of the peptide PMRGGGGYHY.

Genome Sequencing of K4-1 Reveals Its Adaptation to the Arctic Ocean.

The special ecological environment of the Arctic has brought about a large number of salt-tolerant and psychrotolerant microorganisms. We isolated two culturable bacterial strains of the genus ; one from the Arctic ocean, K4-1, and one from the tropical sea, sp. HuA40.

Mechanistic Insight into the Binding and Swelling Functions of Prepeptidase C-Terminal (PPC) Domains from Various Bacterial Proteases.

The bacterial prepeptidase C-terminal (PPC) domain can be found in the C termini of a wide variety of proteases that are secreted by marine bacteria. However, the functions of these PPC domains remain unknown due to a lack of systematic research. Here, the binding and swelling abilities of eight PPC domains from six different proteases were compared systematically via scanning electron microscopy (SEM), enzyme assays, and fluorescence spectroscopy.

Classification and structural insight into vibriolysin-like proteases of Vibrio pathogenicity.

Vibriolysin-like proteases (VLPs) are important virulence agents in the arsenal of Vibrio causing instant cytotoxic effects during infection. Most of Vibrio secreted VLPs show serious pathogenicity, while some species of Vibrio with VLPs are non-pathogenic, like Vibrio tasmaniensis and Vibrio pacinii. To investigate the relation between VLPs and Vibrio pathogenicity, one phylogenetic tree of VLPs was constructed and compared consensus sequences at the N-terminus of VLPs.

Antioxidant and anti-freezing peptides from salmon collagen hydrolysate prepared by bacterial extracellular protease.

Extracted salmon skin collagen was hydrolysed with the free or immobilized extracellular protease of Vibrio sp. SQS2-3. The hydrolysate exhibited anti-freezing activity (>3 kDa) and antioxidant activity (<3000 Da) after ultrafiltration.

Flavobacterium phocarum sp. nov., isolated from soils of a seal habitat in Antarctica.

A Gram-stain-negative, yellow-pigmented, non-flagellated, gliding, rod-shaped, oxidase-negative and catalase-positive bacterium, designated SE14, was isolated from soil on King George Island, South Shetland Islands, Antarctica. Strain SE14 grew at 4-25 °C (optimum, 20 °C), at pH 6.0-9.

New method of detecting hydrophobic interaction between C-terminal binding domain and biomacromolecules.

The C-terminal domains of proteases play crucial roles in hydrolysis, substrate adsorption and targeted binding. Identifying and characterizing interactions between C-terminal domains and biomacromolecules can help to examine the diversity as well as the substrate-binding ability of C-terminal domains and to explore novel functions. The bacterial pre-peptidase C-terminal (PPC) domain is a typical C-terminal domain normally found at the C-terminus of bacterial secreted proteases.

Flavobacterium ardleyense sp. nov., isolated from Antarctic soil.

A Gram-stain-negative, aerobic, yellow-pigmented, non-flagellated, non-gliding, rod-like, oxidase- and catalase-positive bacterium, designated A2-1, was isolated from soil on Ardley Island, South Shetland Islands, Antarctica. Strain A2-1 grew at 4-22 °C (optimum, 10 °C), at pH 6.0-8.

In Situ Demonstration and Characteristic Analysis of the Protease Using Substrate Immersing Zymography.

Zymography, the detection of proteolytic activities on the basis of protein substrate degradation, has been a technique described in the literature for at least in the past 50 years. In this study, we used substrate immersing zymography to analyze proteolysis of proteases. Instead of being directly added into a sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) gel, the substrates were added into the immersing solution after electrophoresis.

Euzebyella marina sp. nov., isolated from seawater.

A Gram-stain-negative, aerobic, yellow-pigmented, non-flagellated, non-gliding, oxidase- and catalase-positive bacterium, designated CY01T, was isolated from seawater of the Yellow Sea. CY01T grew at 15-37 °C (optimum, 30 °C), pH 5-8 (optimum, 6.5-7.

Overview of Antioxidant Peptides Derived from Marine Resources: The Sources, Characteristic, Purification, and Evaluation Methods.

Marine organisms are rich sources of structurally diverse bioactive nitrogenous components. In recent years, numerous bioactive peptides have been identified in a range of marine protein resources, such as antioxidant peptides. Many studies have approved that marine antioxidant peptides have a positive effect on human health and the food industry.

In situ demonstration and characteristic analysis of the protease components from marine bacteria using substrate immersing zymography.

Zymography is a widely used technique for the study of proteolytic activities on the basis of protein substrate degradation. In this study, substrate immersing zymography was used in analyzing proteolysis of extracellular proteases. Instead of being added directly into a sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) gel, the substrates were added into the immersing solution after electrophoresis.

Tenderization effect of cold-adapted collagenolytic protease MCP-01 on beef meat at low temperature and its mechanism.

The enzymes currently used to increase meat tenderness are all mesophilic or thermophilic proteases. This study provides insight into the tenderization effect and the mechanism of a cold-adapted collagenolytic enzyme MCP-01 on beef meat at low temperatures. MCP-01 (10 U of caseinolytic activity) reduced the meat shear force by 23% and increased the relative myofibrillar fragmentation index of the meat by 91.

Review on the angiotensin-I-converting enzyme (ACE) inhibitor peptides from marine proteins.

Hypertension is now a major problem threatening people health in the world. Angiotensin-I-converting enzyme (ACE) plays an important physiological role in regulation of blood pressure via conversion of angiotensin I to angiotensin II. Inhibition of ACE may have an antihypertensive effect as a consequence of a decrease in blood pressure.

Structure and ecological roles of a novel exopolysaccharide from the arctic sea ice bacterium Pseudoalteromonas sp. Strain SM20310.

The structure and ecological roles of the exopolysaccharides (EPSs) from sea ice microorganisms are poorly studied. Here we show that strain SM20310, with an EPS production of 567 mg liter(-1), was screened from 110 Arctic sea ice isolates and identified as a Pseudoalteromonas strain. The EPS secreted by SM20310 was purified, and its structural characteristics were studied.

Genome sequences of type strains of seven species of the marine bacterium Pseudoalteromonas.

There are over 30 species in the marine bacterial genus Pseudoalteromonas. However, our knowledge about this genus is still limited. We sequenced the genomes of type strains of seven species in the genus, facilitating the study of the physiology, adaptation, and evolution of this genus.

Structural and functional characterization of mature forms of metalloprotease E495 from Arctic sea-ice bacterium Pseudoalteromonas sp. SM495.

E495 is the most abundant protease secreted by the Arctic sea-ice bacterium Pseudoalteromonas sp. SM495. As a thermolysin family metalloprotease, E495 was found to have multiple active forms in the culture of strain SM495.

Characterization of bacterial polysaccharide capsules and detection in the presence of deliquescent water by atomic force microscopy.

We detected polysaccharide capsules from Zunongwangia profunda SM-A87 with atomic force microscopy (AFM). The molecular organization of the capsules at the single-polysaccharide-chain level was reported. Furthermore, we found that with ScanAsyst mode the polysaccharide capsules could be detected even in the presence of deliquescent water covering the capsule.

Optimization of fermentation conditions and rheological properties of exopolysaccharide produced by deep-sea bacterium Zunongwangia profunda SM-A87.

Zunongwangia profunda SM-A87 isolated from deep-sea sediment can secrete large quantity of exopolysaccharide (EPS). Response surface methodology was applied to optimize the culture conditions for EPS production. Single-factor experiment showed that lactose was the best carbon source.

Oyster (Crassostrea gigas) hydrolysates produced on a plant scale have antitumor activity and immunostimulating effects in BALB/c mice.

Oyster extracts have been reported to have many bioactive peptides. But the function of oyster peptides produced by proteolysis is still unknown. In this study, the oligopeptide-enriched hydrolysates from oyster (Crassostrea gigas) were produced using the protease from Bacillus sp.