Biotransformasi ketoisophorone dengan menggunakan sel yang tiada pertumbuhan telah dicadangkan dalam kajian ini. Tujuan kajian ini adalah menyiasat kesan penggunaan semula kofaktor dengan menggunakan kepekatan yis yang berbeza dan untuk mengkaji masa kursus bagi 2,6,6,-trimethycyclohex-2-ene-1,4-dione (ketoisophorone) menghasilkan pertengahan yang sepadan seperti 2,6,6-trimethylcyclohexane-1,4-dione [(6R)-levodione] dan 4-hydroxy-2,6,6-trimethylcyclohex-2-ene-1-one [(4S)-phorenol] termasuk produk utama, 4-hydroxy-2,6,6-trimethylcyclohexane [(4R,6R)-actinol] dengan menggunakan sel keseluruhan Saccharomyces cerevisiae yang tiada pertumbuhan. Biotransfromasi fasa cecair telah dijalankan dalam kelalang goncang bersama media sebagai penampan tindak balas pada 37oC dan 150 rpm dengan menggunakan sel S.cerevisiae yang tiada pertumbuhan. Penggunaan semula kofaktor daripada nikotinamide adenina dinukleotida koenzim (NADH/NAD+) and derivatifnya (NADPH/NADP+) telah dikaji dengan menggunakan spekta penyerapan ultraviolet-yang boleh dilihat. Spektrum kofactor telah dipantau panjang gelombang kepada 340nm dan sampel telah dianalisis setiap satu jam sepanjang kajian dijalankan. Bagi penghasilan produk pertengahan, (6R)-levodione mempunyai kepekatan yang lebih tinggi berbanding kepekatan (4S)-phorenol disebabkan persaingan di antara koenzim dan kadar tindak balas ikatan pengurangan karbon-karbon kembar lebih tinggi berbanding tindak balas pengurangan karbonil.
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Biotransformation of ketoisophorone by non-growing cells was proposed from the study. The aim of this research is to investigate the effect of cofactor regeneration by using different yeast’s concentration and to investigate time courses for 2,6,6,-trimethycyclohex-2-ene-1,4-dione (ketoisophorone) to produce the corresponding intermediates of 2,6,6-trimethylcyclohexane-1,4-dione [(6R)-levodione] and 4-hydroxy-2,6,6-trimethylcyclohex-2-ene-1-one [(4S)-phorenol] as well as the main product, 4-hydroxy-2,6,6-trimethylcyclohexane [(4R,6R)-actinol] in a non-growing whole cell Saccharomyces cerevisiae. The liquid-phase biotransformation was carried out in shake-flask with buffer as the reaction medium at 37oC and 150 r.p.m using non-growing cells of S.cerevisiae. The cofactor regeneration of nicotinamide adenine dinucleotide coenzyme (NADH/NAD+) and its derivatives (NADPH/NADP+) was investigated using changes in ultraviolet-visible absorption spectra of these compounds. The spectrum of cofactor was monitored at 340nm wavelength and the sample was analysed for every one hour along the experiment. For the production of intermediates, (6R)-levodione has higher concentration as compared to the concentration of (4S)-phorenol due to the competition of coenzymes and higher rate of carbon-carbon double bond reduction compared to the reaction rate of carbonyl reduction.
Stereospecific biotransformation of 2,6,6 trimethylcyclohex-2-ene-1,4-dione (ketoisophorone) in a non-growing whole cell saccharomyces cerevisiae / Nur Zaherra Zakaria