Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.3.8 (phytase)
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The primary structure of Aspergillus ficuum phytase was deduced from overlaps in peptide sequences. The unglycosylated enzyme is a 441 residue protein with a molecular mass of 48.5-KDa, as calculated from the total covalent structure. The estimated pl of the protein is about 4.76. Of the 19 Asn residues, 9 were found to be glycosylated. The phytase consists of 37% non-polar, 42% polar, 11.5% acidic, and 9.5% basic amino acids. The putative active site of the enzyme containing the sequence RHG is located at the N-terminal region of the molecule and shows homology to the active site of both microbial and mammalian acid phosphatases, and phosphoglycerate mutase.
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PMID:Aspergillus ficuum phytase: complete primary structure elucidation by chemical sequencing. 838 89

PhyA gene products of Aspergillus ficuum (AF) and Peniophora lycii (PL) as expressed in industrial strains of Aspergillus niger and Aspergillus oryzae, respectively, were purified to homogeneity and then characterized for both physical and biochemical properties. The PL phytase is 26 amino acid residues shorter than the AF phytase. Dynamic light scattering studies indicate that the active AF phytase is a monomer while the PL phytase is a dimer. While both of the phytases retained four identical glycosylatable Asn residues, unique glycosylation sites, six for PL and seven for AF phytase, were observed. Global alignment of both the phytases has shown 38% sequence homology between the two proteins. At 58 degrees C and pH 5.0, the PL phytase gave a specific activity of 22,000 nKat/mg as opposed to about 3000 nKat/mg for AF phytase. However, the AF phytase is more thermostable than its counterpart PL phytase at 65 degrees C. Also, AF phytase is more stable at pH 7.5 than the PL phytase. The two phytases differed in K(m) for phytate, K(i) for myo-inositol hexasulfate (MIHS), and pH optima profile. Despite similarities in the active site sequences, the two phytases show remarkable differences in turnover number, pH optima profile, stability at higher temperature, and alkaline pH. These biochemical differences indicate that phytases from ascomycete and basidiomycete fungi may have evolved to degrade phytate in different environments.
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PMID:PhyA gene product of Aspergillus ficuum and Peniophora lycii produces dissimilar phytases. 1265 40