A newly isolated indigenous strain BN10 identified as Pseudomonas aeruginosa was found to produce glycolipid (i.e., rhamnolipid-type) biosurfactants. Two representative rhamnolipidic fractions, RL-1 and RL-2, were separated on silica gel columns and their chemical structure was elucidated by a combination of nuclear magnetic resonance and mass spectroscopy. Subsequently, their cytotoxic effect on cancer cell lines HL-60, BV-173, SKW-3, and JMSU-1 was investigated. RL-1 was superior in terms of potency, causing 50 % inhibition of cellular viability at lower concentrations, as compared to RL-2. Furthermore, the results from fluorescent staining analysis demonstrated that RL-1 inhibited proliferation of BV-173 pre-B human leukemia cells by induction of apoptotic cell death. These findings suggest that RL-1 could be of potential for application in biomedicine as a new and promising therapeutic agent.

Aims:  To isolate a biosurfactant‐producing bacterial strain and to identify and characterize the chemical structure and properties of its biosurfactants. Methods and Results:  The bacterium Rhodococcus wratislaviensis BN38, isolated from soil, was found to produce glycolipid biosurfactants when grown on 2%n‐hexadecane. The glycolipids were isolated by chromatography on silica gel columns and their structures elucidated using a combination of multidimensional NMR and ESI‐MS/MS techniques. The main product was identified as 2,3,4,2′‐trehalose tetraester with molecular mass of 876 g mol−1. It was also noted that the biosurfactant was produced under nitrogen‐limiting conditions and could not be synthesized from water‐soluble substrates. The purified product showed extremely high surface‐active properties. Conclusions:  The glycolipid biosurfactant produced by the alkanothrophic strain R. wratislaviensis BN38 was characterized to be 2,3,4,2′‐trehalose tetraester which exhibited high surfactant activities. Significance and Impact of the Study:  Strain BN38 of R. wratislaviensis is a potential candidate for use in bioremediation applications or in biosurfactant exploration.

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The objective of this study was to isolate and identify the chemical structure of a biosurfactant produced by Nocardia farcinica strain BN26 isolated from soil, and evaluate its in vitro antitumor activity on a panel of human cancer cell lines. Strain BN26 was found to produce glycolipid biosurfactant on n-hexadecane as the sole carbon source. The biosurfactant was purified using medium-pressure liquid chromatography and characterized as trehalose lipid tetraester (THL) by nuclear magnetic resonance spectroscopy and mass spectrometry. Subsequently, the cytotoxic effects of THL on cancer cell lines BV-173, KE-37 (SKW-3), HL-60, HL-60/DOX, and JMSU-1 were evaluated by MTT assay. It was shown that THL exerted concentration-dependent antiproliferative activity against the human tumor cell lines and mediated cell death by the induction of partial oligonucleosomal DNA fragmentation. These findings suggest that THL could be of potential to apply in biomedicine as a therapeutic agent.

A physical organic study reveals general base catalysis by the 2′‐oxyanion of the peptidyl adenosine ethanolysis; this implies a proton‐shuttle role for the 2′‐OH of peptidyl tRNA A76 in the ribosome substrate‐assisted catalytic mechanism.

Glycosylasparaginase is a lysosomal amidase involved in the degradation of glycoproteins. Recombinant human glycosylasparaginase is capable of catalyzing the hydrolysis of the amino acid L-asparagine to L-aspartic acid and ammonia. For the hydrolysis of L-asparagine the K m is 3-4-fold higher and V-mnx 1/5 of that for glycoasparagines suggesting that the full catalytic potential of glycosylasparaginase is not used in the hydrolysis of the free amino acid. L-Asparagine competitively inhibits the hydrolysis of aspartylglucosamine indicating that both the amino acid and glycoasparagine are interacting with the same active site of the enzyme. The hydrolytic mechanism of Lasparagine and glycoasparagines will be discussed.

␤-Aspartyl di-and tripeptides are common constituents of mammalian metabolism, but their formation and catabolism are not fully understood. In this study we provide evidence that glycosylasparaginase (aspartylglucosaminidase), an N-terminal nucleophile hydrolase involved in the hydrolysis of the N-glycosidic bond in glycoproteins, catalyzes the hydrolysis of ␤-aspartyl peptides to form L-aspartic acid and amino acids or peptides. The enzyme also effectively catalyzes the synthesis of ␤-aspartyl peptides by transferring the ␤-aspartyl moiety from other ␤-aspartyl peptides or ␤-aspartylglycosylamine to a variety of amino acids and peptides. Furthermore, the enzyme can use L-asparagine as the ␤-aspartyl donor in the formation of ␤-aspartyl peptides. The data show that synthesis and degradation of ␤-aspartyl peptides are new, significant functions of glycosylasparaginase and suggest that the enzyme could have an important role in the metabolism of ␤-aspartyl peptides.␤-Aspartyl and ␥-glutamyl peptides are normal constituents of mammalian urine (1, 2) and tissues (3). Although ␥-glutamyltransferase (EC 2.3.2.2, GGT) (1) 1 is the key enzyme in the synthesis and hydrolysis of ␥-glutamyl compounds such as glutathione in the ␥-glutamyl cycle (4), little is known about the metabolism of ␤-aspartyl peptides.Glycosylasparaginase (GA; aspartylglucosaminidase;asparagine; ␤-aspartylglucosamine; GlcNAc-Asn) during degradation of glycoproteins. Genetic deficiency of glycosylasparaginase causes a lysosomal storage disease aspartylglycosaminuria (McKusick 208400) that is the most common disorder of glycoprotein degradation in humans and is clinically characterized by severe mental and motor retardation (5, 6).Glycosylasparaginase is a member of the recently described structural superfamily of enzymes termed as N-terminal nucleophile (Ntn) hydrolases (7). The hydrolysis of ␤-aspartylglycosylamines catalyzed by glycosylasparaginase is initiated by the binding of the ␤-aspartyl moiety into the active site of the enzyme through its free ␣-amino and ␣-carboxyl groups (8, 9). The enzyme uses the ␥-hydroxyl and ␣-amino group of its ␤-chain N-terminal threonine as an active site nucleophile and general base in the formation of ␤-aspartyl enzyme, which is subsequently deacylated by water to L-aspartic acid (10, 11). The GA-catalyzed hydrolysis of L-asparagine occurs in a similar manner, resulting in the formation of ␤-aspartyl enzyme and ammonia (12). The mechanism of action of glycosylasparaginase and the structural properties of its substrate-binding site (13) led us to consider that the enzyme might have a role in the metabolism of ␤-aspartyl peptides. In the present study, we demonstrate that synthesis and degradation of ␤-aspartyl peptides are new significant functions of glycosylasparaginase. This suggests that glycosylasparaginase could have an important role in the metabolism of ␤-aspartyl peptides present in body fluids and tissues. EXPERIMENTAL PROCEDURESMaterials-GA was purified to homogeneity from an NIH-3T3 cell line overexpre...

The yeast Candida bombicola ATCC 22214 is well-known to produce mixtures of glycolipids containing the sugar sophorose, the so-called sophorolipids, especially when cultivated on hydrophobic carbon sources as co-substrates. To improve cultivation efficiency, an integrated process was developed using ultrasound separation technology. Since this technology is new for use with C. bombicola, it was first characterized in batch experiments and afterwards implemented in an integrated production process. In this process, separation efficiencies of about 99% C. bombicola cells could be achieved, leading to 8 g/L of nearly cell-free sophorolipid product and a total amount of 73.8 g/L sophorolipids. Furthermore, a technical mixture of unusual branched fatty alcohols containing mainly 2-hexyl-1-decanol was used as co-substrate with glucose in a shake flask study. This resulted in the production of a new product, 1-O-b-glucopyranosyl-2-hexyldecanol, a molecule containing glucose as the sugar moiety and 2-hexyl-1-decanol as a branched hydrophobic side chain.