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ARS Home » Plains Area » Houston, Texas » Children's Nutrition Research Center » Research » Publications at this Location » Publication #77254
Title: HOMOLOGY OF HUMAN INTESTINAL MALTASE-GLUCOAMYLASE (MGA) WITH SUCRASE-ISOMALTASE (SIM).

Author
item Nichols, Buford
item QUARONI, ANDREA - CORNELL UNIVERSITY
item AVERY, STEPHEN - BAYLOR COLL OF MEDICINE
item STERCHI, ERWIN - UNIV. BERNE, SWITZERLAND

Submitted to: Federation of American Societies for Experimental Biology Conference
Publication Type: Abstract Only
Publication Acceptance Date: 2/28/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Interpretive Summary not needed for this 115.

Technical Abstract: Starches are not recommended for young infants' diets because of pancreatic and salivary amylase immaturity. Because intestinal glucoamylase digests starch, it is hypothesized that human MGA may serve as an alternate starch digestion pathway. Overlap exists between in vitro activities of the closely associated SIM and MGA complexes which has prevented direct enzymatic testing of this hypothesis. The objective of our study was the cloning of MGA cDNA to allow expression analysis of individual hydrolytic and binding sites for intestinal enzyme hydrolase activities. Methods: We sequenced 4 CNBr peptides and N terminus from MGA isolated from human mucosa with HBB 2/143/17 mAb. RT used human intestinal RNA. PCR used degenerate primers with specific primers for extensions. Results: A 6515 bp nucleotide coding a 1853 aa, 209 kDA protein was cloned. 92% identity was found between translated and peptide sequences. MGA cDNA is about 70% identical to SIM. MGA peptide has 2 WIDMNE hydrolytic sites shared with SIM. Maltase and glucoamylase domains have internal homologies as does SIM. Conclusion: MGA and SIM are members of the Glycosyl Hydrolase Family 31. The identical WIDMNE sequences suggest a common hydrolytic mechanism with diverse binding regions responsible for the four substrate specificities.