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United States Department of Agriculture

Agricultural Research Service

Title: Conservation of the Kidney Bean Purple Acid Phosphatase Active Site Motif in the Aspergillus Niger (Ficuum) Ph 6.0 Optimum Acid Phosphatase

item Mullaney, Edward
item Ullah, Abul

Submitted to: Biochemical and Biophysical Research Communications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 30, 1997
Publication Date: N/A

Interpretive Summary: Phytic acid is an undesirable component in soybean and several other meals when these are used as feed for monogastric animals. These animals lack an enzyme, phytase, in their digestive tract to break down this compound and release all the phosphorus contained in phytic acid. To make this phosphorus available and not just released in the animal's waste to impact the environment negatively, phytase has now been developed as an animal feed additive. Recently another enzyme, a fungal acid phosphatase, when combined with phytase has been reported to enhance the activity of phytase. We have found that this fungal acid phosphatase has the same active site structure as another group of widely studied enzymes, the kidney bean purple acid phosphatase. This finding will enhance our understanding of the function and structure of this fungal acid phosphatase. This increase knowledge about this enzyme has the potential to assist research on this enzyme and to speed its development as an animal feed additive that can be paired with phytase to increase its activity. The animal feed industry will be the primary beneficaries of this research.

Technical Abstract: Amino acid (AA) sequence analysis of the extracellular Aspergillus niger (ficuum) pH 6.0 optimum acid phosphatase (Apase6) and the kidney bean purple acid phosphatase (KBPAP) revealed, that despite a low degree of total sequence homology, all the essential amino acid residues of the KBPAP's active site are present in Apase6. These regions of Apase6 sequence also display a high degree of homology with the two signature sequence motifs found in metallo-phosphoesterases. The absence of the RHGXRXP sequence motif in Apase6 is further evidence that it is a metallo phosphoesterase and not a histidine acid phosphatase. This conservation of the AA essential for the active site suggests that Apase6 has a similar core structure to that of other purple acid phosphatases (PAP). Application of current PAP research can now be extended to help define the structure and function of Apase6.

Last Modified: 4/22/2015
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