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Megawati Santoso
Bioorganic, Department of Chemistry, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung
Mathematics

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Mechanistic Studies on Photoacylation Megawati Santoso
Jurnal Matematika & Sains Vol 2, No 2 (1997)
Publisher : Institut Teknologi Bandung

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An unprecedented photoacylation method for preparation of acyl- and aroyliron(III) porphyrin complexes has been reported1). This paper present the mechanistic studies on such photoacylation. Detailed mechanistic studies on the photoacylation of chloroiron(III) tetraphenylporphyrin ((TPP)FeCl) suggest "controlled" radical reactions. In the presence of UV light (TPP)FeCl undergoes intramolecular electron transfer to yield (TPP)Fe(II) and chlorine radical. Aldehyde prevents the back electron transfer by trapping the chlorine radical to form the corresponding acyl radical. The photoreduced (TPP)Fe(II) then undergoes oxidative addition with the acyl radical to yield the corresponding acyliron(III) tetraphenylporphyrin complex.
Evaluation of the Ethylene Effect on Well Defined Copper Enzymes Megawati Santoso; Harold M. Goff
Jurnal Matematika & Sains Vol 11, No 1 (2006)
Publisher : Institut Teknologi Bandung

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An indirect approach in studying ethylene binding sites of copper enzymes was carried out since ethylene pleitropic effect in plants and the general affinity of Cu(I) complexes for ethylene suggest a possibility of ethylene binding to various copper enzymes. For this purpose, superoxide dismutase (SOD) and tyrosinase were evaluated using two different methods. H-NMR spectra of three different conditions of SOD (native SOD; reduced SOD; and reduced SOD in the presence of ethylene) were acquired at 25 °C. Activity of mushroom tyrosinase was monitored in the absence of ethylene by evaluating the formation of dopachrome at 475 nm. Three other assay systems were constructed the same way as the control, except one of the reagents (enzyme, DL-DOPA, or sodium phosphate buffer) was each saturated with ethylene prior to mixing all of reagents. Both systems behaved unsatisfactorily for the purpose of evaluation. The coordinated ethylene proton-NMR signal was obscured by the broad HOD signal, due to the partial oxidation of Cu(I) SOD by trace oxygen. Nonetheless, the tyrosinase assay results demonstrated that displacement of oxygen in the assay system by ethylene did not account for the loss of activity. The observed ethylene effect on tyrosinase activity, however, was minimal, since ethylene could produce threshold physiological response at concentration of 6.5 x 10-9 M.
Synthesis of Isothiazolone and 5-Chloroisothiazolone Derivatives Through Simple Amidation and Cyclization Processes Rosalina Wisastra; Frank J. Dekker; Megawati Santoso
Jurnal Matematika & Sains Vol 16, No 2 (2011)
Publisher : Institut Teknologi Bandung

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Several methyl alkanoate substituted isothiazolones and 5-chloroisothiazolones were synthesized using a simple amidation process of 3,3’-dipropionic acid and chlorination during 3,3’-dithiobispropanamide cyclization process, respectively. The results showed that 5-chloroisothiazolones were produced in a good yield (40-70%), whereas the isothiazolones are produced in moderate yield (±20%). Keywords: Isothiazolone, 5-chloroisothiazolone, Organic synthesis, 3,3’-dithiopropionic acid. Sintesa Derivatif Isothiazolon dan 5-Kloroisothiazolon melalui Proses Amidasi dan Siklisasi Sederhana Abstrak Berbagai senyawa turunan dari isothiazolon tersubsitusi oleh metil alkanoat dan 5-kloroisothiazolon disintesis masing-masing melalui proses amidasi sederhana pada senyawa 3,3’-asam dipropionat dan klorinasi saat terjadinya siklisasi 3,3’-dithiobispropanamida. Dalam penelitian ini, 5-kloroisothiazolon tersubsitusi oleh metil alkanoat dapat dihasilkan dengan yield yang memadai (40-70%), sedangkan isothiazolon dapat dihasilkan dengan yield 20%. Kata kunci: Isothiazolon, 5-kloroisothiazolon, Sintesis organik, Asam 3,3’-dithiopropionat
Co-Authors Frank J. Dekker Harold M. Goff Rosalina Wisastra