Linkage specificity

Hatfield, R. D. Vermerris, W. Lignin formation in plants. The dilemma of linkage specificity. Plant Physiol. 2001, 126, 1351-1357. 

Here we have demonstrated that nature of the oligosaccharide product and the glyco-sidic linkage specificity of glucansucrases can be modified by site-directed/random... 

Linkage specificity, in which the enzyme alters the reactivity of a particular type of bond. 

The first group is comprised that of compounds which potentially could be degraded to form G-l-P by phosphorolysis by beta-linkage specific enzymes. They include IPTGlu, cellobiose, sophorose, salicin, and sucrose. Addition of these compounds, or exogenous G-l-P, to Solka Floe fermentations improved maximum cellulase yields from 171 to 309%, and the time period for enzyme synthesis was reduced from 95 to 59% compared with using Solka Floe only. 

Kaludov, N., Brown, K. E., Walters, R. W., Zabner, J. and Chiorini, J. A. (2001). Adeno-associated virus serotype 4 (AAV4) and AAV5 both require sialic acid binding for hemagglutination and efficient transduction but differ in sialic acid linkage specificity. J. Virol. 75, 6884-6893. 

H-bond interactions between the catalyst and substrate were suggested by Campbell to explain why his N-(4/-pyridinyl)-a-methylproline-derived catalysts 16 and 17 (Fig. 8.4) are more enantioselective for N-acylated 1,2-amino alcohols (s = 9-18.8) than for other classes of substrate [95-98]. Recently, Ishihara has designed the histidine derivative 34 as a minimal artificial acylase for the KR of mono-protected cis- 1,2-diols and N-acylated 1,2-amino alcohols [135]. This catalyst incorporates a sulfonamide linkage specifically to allow the NH group to engage as a H-bond donor with the substrates, and gives impressive levels of selectivity with a range of appropriate substrates (Scheme 8.16). 

Marx, S.P., Nosberger, J., and Frehner, M., Seasonal variation of fructan- 3-fructosidase (FEH) activity and characterization of a P-(2-l)-linkage specific FEH from tubers of Jerusalem artichoke (Helianthus tuberosus), New Phytol., 135, 267-277, 1997. 

A second novel aspects approach is substrate directed synthesis. The point of this aspect is that wild-type enzymes could be used to generate more diversity without engineering the enzyme. Therefore acceptor substrates were designed which allow the control of linkage specificity by the enzyme and further chemical reactions and... 

Although some commercially available enzymes are linkage specific, the majority of linkages cannot be defined solely using this approach and/or using the chemical approaches. Hence, linkage analysis experiments are often necessary for rigorous stmeture analysis. 

Organism Enzyme Size (aa) Osidic linkage specificity References... 

Organism Enzyme Size (aa) Osidic linkage specificity a-1,6 a-1,4 a-1,3 a-1,2 References... 

Due to its wide substrate specificity but very limited linkage specificity, the trans-sialidase from T. cruzi has been used for the sialylation of oligosaccharides, yielding Neu5Ac(a2-3)Gal sequences, in glycotechnological experiments [554], discussed in detail in section 6.3. 

Cross-Ring and Other Linkage-Specific Cleavages 142... 

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