Luminal starch substrate "Brake" on maltase-glucoamylase activity is located within the glucoamylase subunit

被引:79
作者
Quezada-Calvillo, Roberto [1 ,2 ,3 ]
Sim, Lyann [4 ,5 ]
Ao, Zihua [6 ,7 ]
Hamaker, Bruce R. [6 ,7 ]
Quaroni, Andrea [8 ]
Brayer, Gary D. [9 ]
Sterchi, Erwin E. [10 ]
Robayo-Torres, Claudia C. [1 ,2 ]
Rose, David R. [4 ,5 ]
Nichols, Buford L. [1 ,2 ]
机构
[1] USDA, ARS, Childrens Nutr Res Ctr, Houston, TX 77030 USA
[2] Baylor Coll Med, Dept Pediat, Houston, TX 77030 USA
[3] Univ Autonoma San Luis Potosi, CIEP Fac Ciencias Quim, San Luis Potosi 78360, Mexico
[4] Univ Toronto, Dept Med Biophys, Toronto, ON M5G 1L7, Canada
[5] Ontario Canc Inst, Div Canc Genom & Proteom, Toronto, ON M5G 1L7, Canada
[6] Purdue Univ, Whistler Ctr Carbohydrate Res, W Lafayette, IN 47907 USA
[7] Purdue Univ, Dept Food Sci, W Lafayette, IN 47907 USA
[8] Cornell Univ, Div Biol Sci, Physiol Sect, Ithaca, NY 14853 USA
[9] Univ British Columbia, Dept Biochem & Mol Biol, Vancouver, BC V6T 1Z3, Canada
[10] Univ Bern, Inst Biochem & Mol Med, CH-3012 Bern, Switzerland
关键词
D O I
10.1093/jn/138.4.685
中图分类号
R15 [营养卫生、食品卫生]; TS201 [基础科学];
学科分类号
100403 ;
摘要
The detailed mechanistic aspects for the final starch digestion process leading to effective alpha-glucogenesis by the 2 mucosal alpha-glucosidases, human sucrase-isomaltase complex (SI) and human maltase-glucoamylase (MGAM), are poorly understood. This is due to the structural complexity and vast variety of starches and their intermediate digestion products, the poorly understood enzyme-substrate interactions occurring during the digestive process, and the limited knowledge of the structure-function properties of SI and MGAM. Here we analyzed the basic catalytic properties of the N-terminal subunit of MGAM (ntMGAM) on the hydrolysis of glucan substrates and compared it with those of human native MGAM isolated by immunochemical methods. In relation to native MGAM, ntMGAM displayed slower activity against maltose to maltopentose (G5) series glucose oligomers, as well as maltodextrins and a-limit dextrins, and failed to show the strong substrate inhibitory "brake" effect caused by maltotriose, maltotetrose, and G5 on the native enzyme. In addition, the inhibitory constant for acarbose was 2 orders of magnitude higher for ntMGAM than for native MGAM, suggesting lower affinity and/or fewer binding configurations of the active site in the recombinant enzyme. The results strongly suggested that the C-terminal subunit of MGAM has a greater catalytic efficiency due to a higher affinity for glucan substrates and larger number of binding configurations to its active site. Our results show for the first time, to our knowledge, that the C-terminal subunit of MGAM is responsible for the MGAM peptide's "glucoamylase" activity and is the location of the substrate inhibitory brake. In contrast, the membrane-bound ntMGAM subunit contains the poorly inhibitable "maltase" activity of the internally duplicated enzyme.
引用
收藏
页码:685 / 692
页数:8
相关论文
共 32 条
[1]   Evidence of native starch degradation with human small intestinal maltase-glucoamylase (recombinant) [J].
Ao, Zihua ;
Quezada-Calvillo, Roberto ;
Sim, Lyann ;
Nichols, Buford L. ;
Rose, David R. ;
Sterchi, Erwin E. ;
Hamaker, Bruce R. .
FEBS LETTERS, 2007, 581 (13) :2381-2388
[2]   Starch with a slow digestion property produced by altering its chain length, branch density, and crystalline structure [J].
Ao, Zihua ;
Simsek, Senay ;
Zhang, Genyi ;
Venkatachalam, Mahesh ;
Reuhs, Bradley L. ;
Hamaker, Bruce R. .
JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY, 2007, 55 (11) :4540-4547
[3]   Glycemic index and obesity [J].
Brand-Miller, JC ;
Holt, SHA ;
Pawlak, DB ;
McMillan, J .
AMERICAN JOURNAL OF CLINICAL NUTRITION, 2002, 76 (01) :281S-285S
[4]  
BRANDMILLER JC, 2004, ASIA PAC J CLIN NU S, V13, pS3
[5]   Subsite mapping of the human pancreatic α-amylase active site through structural, kinetic, and mutagenesis techniques [J].
Brayer, GD ;
Sidhu, G ;
Maurus, R ;
Rydberg, EH ;
Braun, C ;
Wang, YL ;
Nguyen, NT ;
Overall, CH ;
Withers, SG .
BIOCHEMISTRY, 2000, 39 (16) :4778-4791
[6]   Acarbose and 1-deoxynojirimycin inhibit maltose and maltooligosaccharide hydrolysis of human small intestinal glucoamylase-maltase in two different substrate-induced modes [J].
Breitmeier, D ;
Gunther, S ;
Heymann, H .
ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS, 1997, 346 (01) :7-14
[7]   PORCINE PANCREATIC ALPHA-AMYLASE HYDROLYSIS OF HYDROXYETHYLATED AMYLOSE AND SPECIFICITY OF SUBSITE BINDING [J].
CHAN, YC ;
BRAUN, PJ ;
FRENCH, D ;
ROBYT, JF .
BIOCHEMISTRY, 1984, 23 (24) :5795-5800
[8]   SEQUENCE OF THE COMPLETE CDNA AND THE 5' STRUCTURE OF THE HUMAN SUCRASE-ISOMALTASE GENE - POSSIBLE HOMOLOGY WITH A YEAST GLUCOAMYLASE [J].
CHANTRET, I ;
LACASA, M ;
CHEVALIER, G ;
RUF, J ;
ISLAM, I ;
MANTEI, N ;
EDWARDS, Y ;
SWALLOW, D ;
ROUSSET, M .
BIOCHEMICAL JOURNAL, 1992, 285 :915-923
[9]   COLUMN CHROMATOGRAPHY OF HUMAN SMALL-INTESTINAL MALTASE ISOMALTASE AND INVERTASE ACTIVITIES [J].
DAHLQVIST, A ;
TELENIUS, U .
BIOCHEMICAL JOURNAL, 1969, 111 (02) :139-+
[10]   HUMAN INTESTINAL DISACCHARIDASES AND HEREDITARY DISACCHARIDE INTOLERANCE - HYDROLYSIS OF SUROSE, ISOMALTOSE, PALATINOSE (ISOMALTU-MALTO-OLIGOSACCHARIDE) PREPARATION [J].
DAHLQVIST, A ;
AURICCHIO, S ;
PRADER, A ;
SEMENZA, G .
JOURNAL OF CLINICAL INVESTIGATION, 1963, 42 (04) :556-&