Biochemical studies of cocoa bean polyphenol oxidase
Polyphenol oxidase (EC 1.14.18.1) was isolated and partially purified from cocoa beans. The properties of the enzyme were studied. The Michaelis constant Km for catechol was 1 × 10−2 M. The pH optimum of polyphenol oxidase activity assayed with catechol as substrate occurred at pH 6.8 and was charac...
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| Format: | Article |
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John Wiley & Sons
1991
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| Online Access: | http://psasir.upm.edu.my/id/eprint/115537/ |
| _version_ | 1848866802967248896 |
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| author | Pat, M Lee Kong, Hung Lee Abdul Karim, Mohd Ismail |
| author_facet | Pat, M Lee Kong, Hung Lee Abdul Karim, Mohd Ismail |
| author_sort | Pat, M Lee |
| building | UPM Institutional Repository |
| collection | Online Access |
| description | Polyphenol oxidase (EC 1.14.18.1) was isolated and partially purified from cocoa beans. The properties of the enzyme were studied. The Michaelis constant Km for catechol was 1 × 10−2 M. The pH optimum of polyphenol oxidase activity assayed with catechol as substrate occurred at pH 6.8 and was characterised by a relatively high thermal stability, 50% of its activity was lost after heating for 40, 25 and 5 min at 60, 69 and 80°C respectively. The optimum temperature for the enzyme activity with catechol as substrate was around 45°C. The enzyme was reactive towards 3‐(3,4‐dihydroxy phenyl)‐DL‐alanine, 3‐hydroxytyramine hydrochloride and 4‐methyl catechol but showed no activity towards tyrosine, p‐cresol, and 4‐hydroxy‐phenol. A rapid deactivation of the enzyme was observed when catechol of concentration > 40 mM was used as substrate. The enzyme activity was inhibited by ascorbic acid, L‐cysteine, sodium bisulphite and thiourea. |
| first_indexed | 2025-11-15T14:26:24Z |
| format | Article |
| id | upm-115537 |
| institution | Universiti Putra Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-15T14:26:24Z |
| publishDate | 1991 |
| publisher | John Wiley & Sons |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | upm-1155372025-03-07T00:15:58Z http://psasir.upm.edu.my/id/eprint/115537/ Biochemical studies of cocoa bean polyphenol oxidase Pat, M Lee Kong, Hung Lee Abdul Karim, Mohd Ismail Polyphenol oxidase (EC 1.14.18.1) was isolated and partially purified from cocoa beans. The properties of the enzyme were studied. The Michaelis constant Km for catechol was 1 × 10−2 M. The pH optimum of polyphenol oxidase activity assayed with catechol as substrate occurred at pH 6.8 and was characterised by a relatively high thermal stability, 50% of its activity was lost after heating for 40, 25 and 5 min at 60, 69 and 80°C respectively. The optimum temperature for the enzyme activity with catechol as substrate was around 45°C. The enzyme was reactive towards 3‐(3,4‐dihydroxy phenyl)‐DL‐alanine, 3‐hydroxytyramine hydrochloride and 4‐methyl catechol but showed no activity towards tyrosine, p‐cresol, and 4‐hydroxy‐phenol. A rapid deactivation of the enzyme was observed when catechol of concentration > 40 mM was used as substrate. The enzyme activity was inhibited by ascorbic acid, L‐cysteine, sodium bisulphite and thiourea. John Wiley & Sons 1991 Article PeerReviewed Pat, M Lee and Kong, Hung Lee and Abdul Karim, Mohd Ismail (1991) Biochemical studies of cocoa bean polyphenol oxidase. Journal of the Science of Food and Agriculture, 55 (2). pp. 251-260. ISSN 0022-5142; eISSN: 1097-0010 https://onlinelibrary.wiley.com/doi/10.1002/jsfa.2740550210 10.1002/jsfa.2740550210 |
| spellingShingle | Pat, M Lee Kong, Hung Lee Abdul Karim, Mohd Ismail Biochemical studies of cocoa bean polyphenol oxidase |
| title | Biochemical studies of cocoa bean polyphenol oxidase |
| title_full | Biochemical studies of cocoa bean polyphenol oxidase |
| title_fullStr | Biochemical studies of cocoa bean polyphenol oxidase |
| title_full_unstemmed | Biochemical studies of cocoa bean polyphenol oxidase |
| title_short | Biochemical studies of cocoa bean polyphenol oxidase |
| title_sort | biochemical studies of cocoa bean polyphenol oxidase |
| url | http://psasir.upm.edu.my/id/eprint/115537/ http://psasir.upm.edu.my/id/eprint/115537/ http://psasir.upm.edu.my/id/eprint/115537/ |