Glycosidases, modification

A sligth modification of this synthetic methodology allowed the development of a novel route to 4-amino-5-(hydroxymethyl)cyclopentane-l,2,3-triols, some of them display significant glycosidase inhibition properties. In addition, a similar approach starting from L-idose allowed the first polyhydroxylated dspentacine to be prepared.78... 

A very important group of secondary hydroxyl modifications represent fluoroglycosides.104 When they interact with a retaining glycosidase, the highly electronegative fluorine on the carbohydrate ring causes the destabilization of both transition states and the reaction proceeds at a... 

Due to the extreme variety of xylan structures, it is obvious that many kinds of enzymes are needed for their complete hydrolysis in nature. Xylanases (EC 3.2.1.8.) are the polysaccharide hydrolases responsible for the attack of the polymer backbone itself. The total hydrolysis or modification of heteroxylans requires in addition several different exo-glycosidases and esterases. The present knowledge of these enzymes is reviewed in this paper. 

Synthesis and Modification of Carbohydrates Using Glycosidases and Lipases... 

Quiros LM, Aguirrezabalaga I, Olano C et al (1998) Two glycosyltransferases and a glycosidase are involved in oleandomycin modification during its biosynthesis by Streptomyces antibioticus. Mol Microbiol 28 1177-1185... 

As mentioned previously for CS, substrate modifications could be of significant importance as regulating factors in proteolytic degradation of cohesive structures. Walsh and Chapman showed that pretreatment with glycosidases made preparations of stratum corneum more susceptible to cell... 

Secreted proteases and glycosidases may also contribute to a modification of the antibody structure this effect generally happens extracellularly. Karl et al.19 described an acidic protease in cell-free culture supernatant of a hy-bridoma culture with a similar activity of a lysosomal protease. This enzymatic activity could be inhibited by pepstatin A. Investigations of cell-free... 

PTMs Posttranslational modifications (PTMs) are the addition of chemical structures to -R groups of proteins. PTMs also include other processing of proteins such as proteolytic removal of chemical groups like phosphates by phosphatases or sugars by glycosidases or also of primary sequence by proteases. 

Various glycosidases are involved in the modification, biosynthetic processing and trafficking of glycoproteins. Gastanospermin and swainsonine, plant inhibitors of such glycosidases, interfere with glycoprotein biosynthesis and are consequently very toxic (Table 13.1). 

---