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To examine the role of the distal His42 residue in the catalytic mechanism of pea cytosolic ascorbate peroxidase, two site-directed variants were prepared in which His42 was replaced with alanine (H42A) or glutamic acid (H42E). Electronic spectra of the ferric derivatives of H42A and H42E (pH 7.0, l ¼ 0.10 M, 25.0 °C) revealed wavelength maxima [kmax (nm): 397, 509, % 540sh, 644 (H42A); 404, 516, % 538sh, 639 (H42E)] consistent with a predominantly fiveco-ordinate high-spin iron. The specific activity of H42E for oxidation of L-ascorbate (8.2 ± 0.

11p system191 01-06-2013 39 4   Download

Ferredoxin (flavodoxin)-NADP(H) reductases (FNR) are ubiquitous flavoenzymes that deliver NADPH or low potential one-electron donors (ferredoxin, flavodoxin) to redox-based metabolisms in plastids, mitochondria and bacteria. The plant-type reductase is also the basic prototype for one of the major families of flavin-containing electron transferases that display common functional and structural properties.

16p fptmusic 16-04-2013 39 2   Download

Exploring enzymatic mechanisms at a molecular level is one of the major challenges in modern biophysics. Based on enzyme structure data, as obtained by X-ray crystallography or NMR spectroscopy, one can suggest how substrates and products bind for catalysis.

14p vinaphone15 25-02-2013 42 2   Download

Amongst a wide variety of different biochemical reactions in cellular car-bon metabolism, thiamin diphosphate-dependent enzymes catalyze the oxi-dative decarboxylation of 2-keto acids. This type of reaction typically involves redox coupled acyl transfer to CoA or phosphate and is mediated by additional cofactors, such as flavins, iron-sulfur clusters or lipoamide swinging arms, which transmit the reducing equivalents that arise during keto acid oxidation to a final electron acceptor.

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roductoin managers perform the classic functions of management: planning, organizing, directing, and controlling. They also have to keep up with changing technology, monitor costs, and meet budgets. The five most common are inadequate planning and preparation, production, prepass and printing, and distribution. There are four important concepts when selecting type: readability, appropriateness, harmony or appearance, and emphasis. A key is copy casting, knowing ow to fit type into a particular space in a layout....

18p camnhung_1 07-12-2012 87 4   Download

download from wow! php solutions dynamic web design made easy second edition david powers php solutions: dynamic web design made easy, second edition copyright © 2010 by david powers all rights reserved. no part of this work may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage or retrieval system, without the prior written permission of the copyright owner and the publisher.

10p yukogaru14 30-11-2010 179 87   Download