Structural analysis enzymic methods

The substitution pattern of arabinosyl side chains in AX from cereal flours and bran, based on the structural analysis of ohgomer fragments produced by xylan-degrading enzymes of known mode of action, was described by several authors [60-63], and various structural models were created [39,60]. fii a recent study [64] on the fine structure of wheat flour AX, a method was... 

Only a few methods for the specific degradation of polysaccharides were known when an earlier article on structural polysaccharide chemistry appeared in this Series.3 The Smith degradation,4 which has become the most frequently used, had only just been introduced. Since then, a number of specific degradation techniques have been developed. In addition, there have also been some modifications and improvements to existing methods. In this article, chemical methods for specific or selective degradation of polysaccharides, and their applications in structural analysis, will be discussed. Enzymic methods, which may be of considerable value, have already been treated in this Series.5... 

A relatively common feature of many problems involving molecular weight determination of biopolymers is that of association-dissociation equilibrium. Subunit structure of enzyme proteins is well recognized (1), and methods of dissociation of subunits to obtain monomer molecular weight are widely utilized (2). A previous paper described the application of an equilibrium gel partition method to the analysis of macromolecular association in a monomer-dimer case (3). The experimental parameters in a system utilizing the Sephadex series of gel filtra-... 

Since the methylation analysis of raffinose by Haworth and coworkers,114 the structure assigned (4) has been confirmed by chemical and enzymic methods.115... 

Earlier work in this field [28] indicated that acetylcholinesterase enzymes would be suitable biomolecules for the purpose of pesticide detection, however, it was found that the sensitivity of the method varied with the type and source of cholinesterase used. Therefore the initial thrust of this work was the development of a range of enzymes via selective mutations of the Drosophila melanogaster acetylcholinesterase Dm. AChE. For example mutations of the (Dm. AChE) were made by site-directed mutagenesis expressed within baculovirus [29]. The acetylcholinesterases were then purified by affinity chromatography [30]. Different strategies were used to obtain these mutants, namely (i) substitution of amino acids at positions found mutated in AChE from insects resistant to insecticide, (ii) mutations of amino acids at positions suggested by 3-D structural analysis of the active site,... 

From the mere fact that CF, can be released from the membrane by EDTA treatment and the enzyme stays in solution without detergents, it is apparent that the catalytic sector has minimal, if any, direct interaction with the lipids of the chloroplast membrane. It is a globular protein that is held to the surface of the membrane via interaction with the membrane sector. Recently it was shown that the y subunit is in immediate contact with the membrane sector and the 8 and e subunits may induce proper binding for catalysis [17,18], The enzyme contains a few well-defined sites that were used for localization experiments by the method of fluorescent energy transfer [19,56-61], These studies revealed the position of those sites and helped to localize the various subunits of CF, in space relative to the chloroplast membranes (for a model of CF, see Refs. 61 and 62). These experiments are awaiting analysis of the amino acid sequence of the y subunit that is now under investigation in Herrmann s laboratory [148], Definite structural analysis could be obtained only after good crystals of the enzyme become available. 

The early part of 20 century witnessed a sudden outburst of knowledge in chemical analysis, separation methods, electronic instrumentation for biological studies (X-ray diffraction, electron microscope, etc.) which ultimately resulted in understanding the structure and function of several key molecules involved in life processes such as proteins, enzymes, DNA and RNA. 

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