Transition polypeptide

The induction of anaerobic treatment synthesis occurs in two phases. During the first few hours of anaerobic treatment there is a transition period during which there is a rapid increase in the synthesis of a class of polypeptides with an approximate molecular weight of 33 kDa (Fig. 3). These have, been referred to as the transition polypeptides (TPs) as they represent most of the protein synthesis occurring in early anaerobiosis. 

Fig. 3. Protein synthesis in a maize primary root during ( ) one hr pulse labelling with [ HJleucine under aerobic conditions (b)-(e) pulse labelling with [ HJIeucine during the specified times under anaerobic conditions. The arrow labelled TPs indicates the position of the transition polypeptides. The unlabelled arrow indicates the position of alcohol dehydrogenase 1 (ADHl). From Sachs et al. (1980).

Averaged principal moments, a , of the Inertia tensor are obtained for polypeptides undergoing a helix-coil transition. Polypeptide chains containing 101, 201,401,... 

Another class of polymers equipped with azobenzene moieties comprises a-helical polypeptides, in particular pQly(L-glutamate)s and poIy(L-lysine)s. In solution, these azobenzene-modified polypeptides can undergo photoinduced helix-coil transitions. Polypeptides partially (30 to 50%) substituted with azobenzene moieties are surface active and form stable monolayers. Because of the partial substitution, there is sufficient free volume, and the azobenzene moieties can be isomerized in the monolayer. The photoisomerization changes the area per molecule, and the monolayer shows a photomechanical effect. LBK films of a photosensitive poly(L-lysine) with 31 mol... 

The basic features of folding can be understood in tenns of two fundamental equilibrium temperatures that detennine tire phases of tire system [7]. At sufficiently high temperatures (JcT greater tlian all tire attractive interactions) tire shape of tire polypeptide chain can be described as a random coil and hence its behaviour is tire same as a self-avoiding walk. As tire temperature is lowered one expects a transition at7 = Tq to a compact phase. This transition is very much in tire spirit of tire collapse transition familiar in tire theory of homopolymers [10]. The number of compact... 

The enzyme provides a general base, a His residue, that can accept the proton from the hydroxyl group of the reactive Ser thus facilitating formation of the covalent tetrahedral transition state. This His residue is part of a catalytic triad consisting of three side chains from Asp, His, and Ser, tvhich are close to each other in the active site, although they are far apart in the amino acid sequence of the polypeptide chain (Figure 11.6). 

Teramoto, A. and Fujita, H. Conformation-dependet Properties of Synthetic Polypeptides in the Helix-Coil Transition Region. Vol. 18, pp. 65— 149. 

Fig. 10. The putative transition-state complex formed between the Fe protein MgADP AlFj and the MoFe protein. For simplicity only one a/3 pair of subunits of the MoFe protein is shown. The polypeptides are indicated by ribbon diagrams and the metal-sulfur clusters and MgADP AlFi" by space-filling models (MOLSCRIPT (196)). The figure indicates the spatial relationship between the metal-sulfur clusters of the two proteins in the complex.

The ionized forms of polypeptides exhibit many characteristics in common therefore, we have studied them under various conditions. The most interesting observation is the transition of a polyelectrolyte brush found by changing the polyelectrolyte chain density. The brush layers have been prepared by means of the LB film deposition of an amphiphile, 2C18PLGA(48), at pH 10. Mixed monolayers of 2C18PLGA(48) and dioctadecylphos-phoric acid, DOP, were used in order to vary the 2C18PLGA(48) content in the monolayer. 

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