Score: 6.00 | Title: Functional roles of protein domains on rice alpha-amylase activity .
| Author: Terashima M Hosono M Katoh S | Journal: Appl . Microbiol . Biotechnol . Citation: V : 47 ( 4 ) P : 364-7 Year: 1997 Type: ARTICLE | Literature: oryza Field: abstract Doc ID: pub9163949 Accession (PMID): 9163949 | Abstract: Characteristics of two rice alpha-amylases Amy1A and Amy3D , and those of two chimeric enzymes Amy1A/3D and Amy3D/1A , engineered from the two isozymes , were compared in the light of the functional roles of protein domains in alpha-amylase .
The enzymes that have an Amy1A-type N-terminal domain , Amy1A and Amy1A/3D , showed high activity against soluble starch , while the enzymes that have an Amy3D-type barrel structure , Amy3D and Amy1A/3D , showed high activity in oligosaccharide hydrolysis .
Rigidity of protein folding also significantly affected the enzyme activity in both soluble starch and oligosaccharide hydrolysis .
Thus , the present work suggests that the structure of the N-terminal domain is important for stability and soluble starch hydrolysis , while the barrel structure that forms the active site significantly affects enzyme activities in oligosaccharide degradation .
We have already characterized two rice alpha-amylase isozymes , Amy1A and Amy3D , and a chimeric enzyme engineered from these two isozymes , Amy1A/3D ( Terashima et al 1995 , 1996a , b ) .
In spite of the high homology ( 70% ) of their amino acid sequences , Amy1A and Amy3D showed distinct differences in their enzymatic characteristics .
The chimeric enzyme Amy1A/3D , which consists of an Amy1A-type N-terminal domain and an Amy3D-type barrel structure , inherited enzymatic characteristics from the both isozymes .
In this work , one other chimeric enzyme , Amy3D/1A , which is the counterpart of Amy1A/3D , has been characterized .
The characteristics of these four enzymes are discussed in the light of the functional roles of protein domains . | Matching Sentences: [ Sen. 2, subscore: 2.00 ]: The enzymes that have an Amy1A-type N-terminal domain , Amy1A and Amy1A/3D , showed high activity against soluble starch , while the enzymes that have an Amy3D-type barrel structure , Amy3D and Amy1A/3D , showed high activity in oligosaccharide hydrolysis . [ Sen. 1, subscore: 1.00 ]: Characteristics of two rice alpha-amylases Amy1A and Amy3D , and those of two chimeric enzymes Amy1A/3D and Amy3D/1A , engineered from the two isozymes , were compared in the light of the functional roles of protein domains in alpha-amylase . [ Sen. 5, subscore: 1.00 ]: We have already characterized two rice alpha-amylase isozymes , Amy1A and Amy3D , and a chimeric enzyme engineered from these two isozymes , Amy1A/3D ( Terashima et al 1995 , 1996a , b ) . [ Sen. 6, subscore: 1.00 ]: In spite of the high homology ( 70% ) of their amino acid sequences , Amy1A and Amy3D showed distinct differences in their enzymatic characteristics . [ Sen. 7, subscore: 1.00 ]: The chimeric enzyme Amy1A/3D , which consists of an Amy1A-type N-terminal domain and an Amy3D-type barrel structure , inherited enzymatic characteristics from the both isozymes .
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Score: 4.00 | Title: Characterization of rice alpha-amylase isozymes expressed by Saccharomyces cerevisiae .
| Author: Terashima M Katoh S Thomas BR Rodriguez RL .
| Journal: Appl . Microbiol . Biotechnol . Citation: V : 43 ( 6 ) P : 1050-5 Year: 1995 Type: ARTICLE | Literature: oryza Field: abstract Doc ID: pub8590656 Accession (PMID): 8590656 | Abstract: Two rice alpha-amylase isozymes , AmylA and Amy3D , were produced by secretion from genetically engineered strains of Saccharomyces cerevisiae .
They have distinct differences in enzymatic characteristics that can be related to the physiology of the germinating rice seed .
The rice isozymes were purified with immunoaffinity chromatography .
The pH optima for Amy3D ( pH optimum 5 . 5 ) and Amy1A ( pH optimum 4 . 2 ) correlate with the pH of the endosperm it issue at the times in rice seedling development when these isozymes are produced .
Amy3D showed 10-14 times higher reactivity to oligosaccharides than Amy1A .
Amy1A , on the other hand , showed higher reactivity to soluble starch and starch granules than Amy3D .
These results suggest that the isozyme Amy3D , which is expressed at an early stage of germination , produces sugars from soluble starch during the early stage of seed germination and that the isozyme Amy1A works to initiate hydrolysis of the starch granules . | Matching Sentences: [ Sen. 4, subscore: 1.00 ]: The pH optima for Amy3D ( pH optimum 5 . 5 ) and Amy1A ( pH optimum 4 . 2 ) correlate with the pH of the endosperm it issue at the times in rice seedling development when these isozymes are produced . [ Sen. 5, subscore: 1.00 ]: Amy3D showed 10-14 times higher reactivity to oligosaccharides than Amy1A . [ Sen. 6, subscore: 1.00 ]: Amy1A , on the other hand , showed higher reactivity to soluble starch and starch granules than Amy3D . [ Sen. 7, subscore: 1.00 ]: These results suggest that the isozyme Amy3D , which is expressed at an early stage of germination , produces sugars from soluble starch during the early stage of seed germination and that the isozyme Amy1A works to initiate hydrolysis of the starch granules .
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