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...
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Published: |
John Wiley & Sons
1991
|
| Online Access: | http://psasir.upm.edu.my/id/eprint/116312/ |
| _version_ | 1848866974117920768 |
|---|---|
| author | Lee, Pat M Lee, Kong‐Hung Ismail, Mohd Karim, Abdul |
| author_facet | Lee, Pat M Lee, Kong‐Hung Ismail, Mohd Karim, Abdul |
| author_sort | Lee, Pat M |
| 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 | 2025-11-15T14:29:07Z |
| format | Article |
| id | upm-116312 |
| institution | Universiti Putra Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-15T14:29:07Z |
| publishDate | 1991 |
| publisher | John Wiley & Sons |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | upm-1163122025-03-25T01:28:04Z http://psasir.upm.edu.my/id/eprint/116312/ Biochemical studies of cocoa bean polyphenol oxidase Lee, Pat M Lee, Kong‐Hung Ismail, Mohd Karim, Abdul 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 Lee, Pat M and Lee, Kong‐Hung and Ismail, Mohd and Karim, Abdul (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 | Lee, Pat M Lee, Kong‐Hung Ismail, Mohd Karim, Abdul 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/116312/ http://psasir.upm.edu.my/id/eprint/116312/ http://psasir.upm.edu.my/id/eprint/116312/ |