Amino acid sequences evolution

It should be noted that in almost all cases only one fold exists for any given sequence. The uniqueness of the native state arises from the fact that the interactions that stabilize the native strucmre significantly destabilize alternate folds of the same amino acid sequence. That is, evolution has selected sequences with a deep energy minimum for the native state, thus eliminating misfolded or partly unfolded structures at physiological temperatures. 

Arthur Lesk and Cyrus Chothia at the MRC Laboratory of Molecular Biology in Cambridge, UK, compared the family of globin strucfures with the aim of answering two general questions How can amino acid sequences that are very different form proteins that are very similar in their three-dimensional structure What is the mechanism by which proteins adapt to mutations in the course of their evolution ... 

S. W. Fox (from 1984, director of the Institute for Molecular and Cellular Evolution of the University of Miami) made the highly controversial suggestion that the amino acid sequences in the proteinoids are not random. Nakashima prepared a thermal polymer from glutamic acid, glycine and tyrosine the analysis showed that two tyrosine-containing tripeptides had been formed pyr-Glu-Gly-Tyr and pyr-Glu-Tyr-Gly (Nakashima et al 1977). The result was confirmed (Hartmann, 1981). A closer examination of the reaction mechanism showed that the formation of these two tripeptides under the reaction conditions used depends on three parameters ... 

Fig. 1 shows sections from the amino acid sequences of the two subunits, using the single-letter notation (see p. 60). A common precursor gene was probably duplicated at some point in evolution. The two genes then continued to develop further independently of each other through mutation and selection. 

Laccase, 36 318, 329, 40 122 see also Blue copper oxidases amino-acid sequences, 40 141 anaerobic reduction, 40 158-160 biological function, 40 124 electrochemistry, 36 360 fungal, 40 145-152 evolution, 40 153-154 inhibition, 40 162 kinetic properties, 40 157-162 molecular and spectroscopic properties, 40 125-126... 

The activity of 2,3-oxidosqualene cyclases is associated with microsomes, indicating their membrane-bound nature. However, the predicted amino acid sequences of these enzymes generally lack signal sequences and obvious transmembrane domains. Addition of hydrophobic membrane-localising regions to OSCs during evolution may have removed selection pressures that maintained alternate mechanisms for membrane localisation [33]. Consistent with this, there is a non-polar plateau on the surface of the A. acidocaldarius SC enzyme which is believed to be immersed in the centre of the membrane. The squalene substrate for SC is likely to diffuse from the membrane interior into the central cavity of the enzyme via this contact region [55,56]. 

Suzuki, T. Nishimura, Y. Umekawa, M. Yamamoto, Y Kawamichi, H. Furukohri, T. Evolution of phosphagen kinase VII. Isolation of glycocyamine kinase from the polychaete Neanthes diversicolor and the cDNA-derived amino acid sequences of a and chains. J. Protein Chem., 18, 13-19 (1999)... 

Suzuki, T. Kawasaki, Y Furukohri, T. Evolution of phosphagen kinase. Isolation, characterization and cDNA-derived amino acid sequence of two-domain arginine kinase from the sea anemone Anthopleura japonicus. Biochem. J., 328 (Pt 1), 301-306 (1997)... 

Protein sequences are a rich source of information about protein structure and function, as well as the evolution of life on this planet. Sophisticated methods are being developed to trace evolution by analyzing the resultant slow changes in the amino acid sequences of homologous proteins. 

Schewale, J. G., Sinha, S. K. and Brew, K. 1984. Evolution of a-lactalbumins. The complete amino acid sequence of the a-lactalbumin from a marsupial (Macropus rufogri-seus) and corrections to regions of sequence in bovine and goat a-lactalbumins. J. BioL Chem. 259, 4947-4956. 

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