▪ Abstract In procaryotes, l-carnitine may be used as both a carbon and nitrogen source for aerobic growth, or the carbon chain may be used selectively following cleavage of trimethylamine. Under anaerobic conditions and in the absence of preferred substrates, some bacteria use carnitine, via crotonobetaine, as an electron acceptor. Formation of trimethylamine and γ-butyrobetaine (from reduction of crotonobetaine) from l-carnitine by enteric bacteria has been demonstrated in rats and humans. Carnitine is not degraded by enzymes of eukaryotic origin. In higher organisms, carnitine has specific functions in intermediary metabolism. Concentrations of carnitine and its esters in cells of eukaryotes are rigorously maintained to provide optimal function. Carnitine homeostasis in mammals is preserved by a modest rate of endogenous synthesis, absorption from dietary sources, efficient reabsorption, and mechanisms present in most tissues that establish and maintain substantial concentration gradients between intra...

Carnitine metabolism and its regulation in microorganisms and mammals

Chitin is the second most abundant organic and renewable source in nature, after cellulose. Chitinases are chitin-degrading enzymes. Chitinases have important biophysiological functions and immense potential applications. In recent years, researches on fungal chitinases have made fast progress, especially in molecular levels. Therefore, the present review will focus on recent advances of fungal chitinases, containing their nomenclature and assays, purification and characterization, molecular cloning and expression, family and structure, regulation, and function and application.

Review of fungal chitinases.

Peroxisomes contribute to several crucial metabolic processes such as β-oxidation of fatty acids, biosynthesis of ether phospholipids and metabolism of reactive oxygen species, which render them indispensable to human health and development. Peroxisomes are highly dynamic organelles that rapidly assemble, multiply and degrade in response to metabolic needs. In recent years, the interest in peroxisomes and their physiological functions has significantly increased. This review intends to highlight recent discoveries and trends in peroxisome research, and represents an update as well as a continuation of a former review article. Novel exciting findings on the biological functions, biogenesis, formation and degradation of peroxisomes, on peroxisomal dynamics and division, as well as on the interaction and cross-talk of peroxisomes with other subcellular compartments are addressed. Furthermore, recent findings on the role of peroxisomes in the brain are discussed.

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The peroxisome: an update on mysteries

Sorbitol, a polyol found in many fruits, is of increasing industrial interest as a sweetener, humectant, texturizer and softener. At present, it is produced chemically. The bacterium Zymomonas mobilis is able to produce sorbitol and gluconic acid from fructose and glucose, respectively. This is possible in a one-step reaction via a glucose-fructose oxidoreductase so far only known from Z. mobilis. The possibilities for the industrial production of sorbitol by Z. mobilis are discussed, and compared with the current chemical production method as well as other microbiological processes.

The biotechnological production of sorbitol

Non-sequential processes which allow the transformation of a racemate into a single stereoisomeric product without the occurrence of an "undesired" isomer are classified according to their underlying stereochemistry. A re-definition of the term "de-racemization" is proposed.

Non-sequential processes for the transformation of a racemate into a single stereoisomeric product: proposal for stereochemical classification.

Characterisation of partially purified milk-clotting enzyme from Solanum dubium Fresen seeds

https://www.researchgate.net/file.PostFileLoader.html?id=540513d0cf57d743378b45be&assetKey=AS%3A273590816051209%401442240542395

Dubiumin, a chymotrypsin-like serine protease from the seeds of Solanum dubium Fresen.

In this study we investigated the pH stability and effect of salts on the activity of a partially purified enzyme from Solanum dubium seeds as well as its hydrolytic power on caseins and caseins components. The seeds of S. dubium were blended and extracted using 50 g/L NaCl in 50 mmol/L acetate buffer, pH 5.0. The enzyme was then partially purified using ammonium sulfate. The results obtained showed that both NaCl and CaCl2 enhanced the proteolytic activity of the enzyme and the enhancement was found to be significant when NaCl was used. Moreover, the stimulatory effect was found to be concentration dependent. The proteolysis of bovine whole casein and casein subunits by the enzyme during incubation was studied by SDS–PAGE. The results obtained revealed that both κ-casein and β-casein are the most susceptible to hydrolysis than α-casein. The three main casein components α-, β-, and κ-caseins were sensitive to the action of the enzyme and the order of hydrolysis obtained was κ- casein, β- casein, and α- caseins.

pH stability and influence of salts on activity of a milk-clotting enzyme from Solanum dubium seeds and its enzymatic action on bovine caseins

The hexactinellids are a diverse group of predominantly deep sea sponges that synthesize elaborate fibrous skeletal systems of amorphous hydrated silica. As a representative example, members of the genus Euplectella have proved to be useful model systems for investigating structure-function relationships in these hierarchically ordered siliceous network-like composites. Despite recent advances in understanding the mechanistic origins of damage tolerance in these complex skeletal systems, the details of their synthesis have remained largely unexplored. Here, we describe a previously unidentified protein, named "glassin," the main constituent in the water-soluble fraction of the demineralized skeletal elements of Euplectella. When combined with silicic acid solutions, glassin rapidly accelerates silica polycondensation over a pH range of 6-8. Glassin is characterized by high histidine content, and cDNA sequence analysis reveals that glassin shares no significant similarity with any other known proteins. The deduced amino acid sequence reveals that glassin consists of two similar histidine-rich domains and a connecting domain. Each of the histidine-rich domains is composed of three segments: an amino-terminal histidine and aspartic acid-rich sequence, a proline-rich sequence in the middle, and a histidine and threonine-rich sequence at the carboxyl terminus. Histidine always forms HX or HHX repeats, in which most of X positions are occupied by glycine, aspartic acid, or threonine. Recombinant glassin reproduces the silica precipitation activity observed in the native proteins. The highly modular composition of glassin, composed of imidazole, acidic, and hydroxyl residues, favors silica polycondensation and provides insights into the molecular mechanisms of skeletal formation in hexactinellid sponges.

https://www.pnas.org/content/pnas/112/37/11449.full.pdf

Glassin, a histidine-rich protein from the siliceous skeletal system of the marine sponge Euplectella, directs silica polycondensation

A novel type of trehalose phosphorylase was found in a basidiomycete. Flammulina velutipes. The enzyme catalyzes both the reversible phosphorolysis of trehalose to form α-glucose 1-phosphate and glucose and also the synthesis of trehalose. Comparison of the specific activity of trehalose phosphorylase with that of trehalase suggested that the function of the former enzyme was more important in the fruit-bodies of this fungus.

Nobuhiro Mori

Papers

Characterisation of partially purified milk-clotting enzyme from Solanum dubium Fresen seeds

Dubiumin, a chymotrypsin-like serine protease from the seeds of Solanum dubium Fresen.

pH stability and influence of salts on activity of a milk-clotting enzyme from Solanum dubium seeds and its enzymatic action on bovine caseins

Glassin, a histidine-rich protein from the siliceous skeletal system of the marine sponge Euplectella, directs silica polycondensation

α-Glucose-1-phosphate formation by a novel trehalose phosphorylase from Flammulina velutipes