RESUMO
A library of artificial random proteins of 141 amino acid residues of which 95 are random and which includes the 20 kinds of amino acids was prepared. Out of the 25 identified random proteins, 5 were soluble in the cell lysate, indicating that about 20% of the random proteins expressed in Escherichia coli are expected to be soluble. The soluble random proteins RP3-42 and RP3-45 and insoluble RP3-70 were purified. The solubility of the purified form is the same as that in the cell lysate.
Assuntos
Proteínas/química , Sequência de Aminoácidos , Aminoácidos/análise , Composição de Bases , Sequência de Bases , Evolução Molecular , Biblioteca Gênica , Dados de Sequência Molecular , Proteínas/genética , Proteínas Recombinantes de Fusão/química , Análise de Sequência de DNA , SolubilidadeRESUMO
The structural and catalytic properties of two soluble random proteins, RP3-42 and RP3-45, of 141 amino acid residues were investigated. Although no marked secondary structure was detected by CD spectrum, sedimentation equilibrium and small-angle X-ray scattering studies showed that they form an oligomeric structure and are as compact as the molten globule. The random proteins have low but distinct esterase activity; the values of the second-order rate constant for the hydrolysis of p-nitrophenol were 0.78 and 1.39 M(-1) s(-1) for RP3-42 and RP3-45, respectively. The differences in the properties of the random and the native proteins are discussed from the evolutionary point of view.
Assuntos
Proteínas/química , Sequência de Aminoácidos , Sulfato de Amônio , Catálise , Precipitação Química , Dados de Sequência Molecular , Oligopeptídeos/química , Estrutura Secundária de Proteína , SolubilidadeRESUMO
A library of artificial proteins of 141 amino acid residues, of which 95 are random and which include 20 kinds of amino acids, was prepared. As the properties of the artificial random proteins are free from the evolutionary constraint, they can be used as a standard to discriminate the specialized properties of natural proteins. Out of the 25 identified random proteins, 5 are soluble in the cell lysate, indicating that about 20% of the random proteins expressed in Escherichia coli are expected to be soluble. Therefore, as natural soluble or insoluble proteins can arise from the line of soluble or insoluble ancestry, respectively, solubility does not seem a specialized property of natural proteins. The soluble random proteins RP3-42 and RP3-45 were purified and their properties were investigated.
Assuntos
Biblioteca de Peptídeos , Proteínas/química , Sequência de Aminoácidos , Sequência de Bases , Clonagem Molecular , Escherichia coli , Biblioteca Gênica , Reação em Cadeia da Polimerase/métodos , Biossíntese de Proteínas , Engenharia de Proteínas , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/química , SolubilidadeRESUMO
Through selective cultivation with 6-aminohexanoate linear dimer, a by-product of nylon-6 manufacture, as the sole source of carbon and nitrogen, Pseudomonas aeruginosa PAO, which initially has no enzyme activity to degrade this xenobiotic compound, was successfully expanded in its metabolic ability. Two new enzyme activities, 6-aminohexanoate cyclic dimer hydrolase and 6-aminohexanoate dimer hydrolase, were detected in the adapted strains.