TY - JOUR
T1 - Nitrospiropyran-modified α-chymotrypsin, a photostimulated biocatalyst in an organic solvent
T2 - Effects of bioimprinting
AU - Lion-Dagan, Mazzi
AU - Willner, Itamar
PY - 1997/8/15
Y1 - 1997/8/15
N2 - α-Chymotrypsin (α-Chy) is modified with the nitrospiropyran active ester 1-( β-carboxyethyl-N-hydroxysuccinimide ester)-3,3-dimethyl-6′-nitrospiro[indoline-2,2′-2H-benzopyran] (1) to yield a photoisomerizable enzyme. The modified enzyme is reversibly photoisomerizable between the nitrospiropyran state, α-Chy-SP, and the nitromerocyanine state, α-Chy-MR, that exists in an aqueous phase at neutral pH ≤ 8.0 in the protonated state, α-Chy-MRH+. The two photoisomer states reveal in water similar biocatalytic activities for hydrolysis of N-acetyl-L-phenylalanine ethyl ester (3) to yield N-acetyl-L-phenylalanine (2). The photoisomerizable enzyme reveals photoswitchable activities in an organic phase consisting of cyclohexane, and esterification of 2 by ethanol is 3.4-fold faster in the presence of α-Chy-SP than by α-Chy-MR. Bioimprinting of the enzyme-substrate 2 into the biocatalyst via precipitation of the enzyme in the presence of the substrate from an aqueous solution yields a substantially more active biocatalyst in the organic phase. The bioimprinted photoisomerizable enzyme reveals photoswitchable biocatalytic activities in the organic phase, but the switching efficiency is lower than that observed for the non-imprinted biocatalyst. The bioimprinted α-Chy-SP is 2.2-fold more active than α-Chy-MR for hydrolysis of 3. The lack of photoswitchable activities of the photoisomerizable enzyme in aqueous media compared to its photostimulated activities in the organic phase is attributed to the enhanced structural perturbation of the protein by the photoisomerizable units in the organic phase. The enhanced activity of the bioimprinted enzyme in the organic phase and its lower photoswitching efficiency compared to the non-imprinted photoisomerizable enzyme are attributed to the rigidification of the protein and its active site by the imprinting process.
AB - α-Chymotrypsin (α-Chy) is modified with the nitrospiropyran active ester 1-( β-carboxyethyl-N-hydroxysuccinimide ester)-3,3-dimethyl-6′-nitrospiro[indoline-2,2′-2H-benzopyran] (1) to yield a photoisomerizable enzyme. The modified enzyme is reversibly photoisomerizable between the nitrospiropyran state, α-Chy-SP, and the nitromerocyanine state, α-Chy-MR, that exists in an aqueous phase at neutral pH ≤ 8.0 in the protonated state, α-Chy-MRH+. The two photoisomer states reveal in water similar biocatalytic activities for hydrolysis of N-acetyl-L-phenylalanine ethyl ester (3) to yield N-acetyl-L-phenylalanine (2). The photoisomerizable enzyme reveals photoswitchable activities in an organic phase consisting of cyclohexane, and esterification of 2 by ethanol is 3.4-fold faster in the presence of α-Chy-SP than by α-Chy-MR. Bioimprinting of the enzyme-substrate 2 into the biocatalyst via precipitation of the enzyme in the presence of the substrate from an aqueous solution yields a substantially more active biocatalyst in the organic phase. The bioimprinted photoisomerizable enzyme reveals photoswitchable biocatalytic activities in the organic phase, but the switching efficiency is lower than that observed for the non-imprinted biocatalyst. The bioimprinted α-Chy-SP is 2.2-fold more active than α-Chy-MR for hydrolysis of 3. The lack of photoswitchable activities of the photoisomerizable enzyme in aqueous media compared to its photostimulated activities in the organic phase is attributed to the enhanced structural perturbation of the protein by the photoisomerizable units in the organic phase. The enhanced activity of the bioimprinted enzyme in the organic phase and its lower photoswitching efficiency compared to the non-imprinted photoisomerizable enzyme are attributed to the rigidification of the protein and its active site by the imprinting process.
KW - Bioimprinting
KW - Nitrospiropyran
KW - Photoisomerizable materials
KW - Photoswitchable enzyme
KW - α-chymotrypsin
UR - http://www.scopus.com/inward/record.url?scp=0031571554&partnerID=8YFLogxK
U2 - 10.1016/S1010-6030(97)00083-X
DO - 10.1016/S1010-6030(97)00083-X
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AN - SCOPUS:0031571554
SN - 1010-6030
VL - 108
SP - 247
EP - 252
JO - Journal of Photochemistry and Photobiology A: Chemistry
JF - Journal of Photochemistry and Photobiology A: Chemistry
IS - 2-3
ER -