Carotenoids Other Than Vitamin A–iii. Third International Symposium On Carotenoids Other Than Vitamin A

UNION INTERNATIONALE DE CHIMIE PURE ET APPLIQUEE DIVISION DE CHIMIE ORGANIQUE avec MINISTERE ROUMAIN DE L'EDUCATION et LACADEMIE DE LA R.S. ROUMANIE LES CAROTENOIDES AUTRE QUE VITAMINE A—III Conferences plenieres presentees au TROISIEME SYMPOSIUM INTERNATIONAL SUR LES CAROTENOIDES AUTRE QUE VITAMINE A ά Cluj, Roumanie 4-7 septembre 1972 LONDRES BUTTERWORTHS INTERNATIONAL UNION OF PURE AND APPLIED CHEMISTRY ORGANIC CHEMISTRY DIVISION in conjunction with THE ROMANIAN MINISTRY OF EDUCATION and THE ACADEMY OF THE S.R. ROMANIA CAROTENOIDS OTHER THAN VITAMIN A—III Plenary lectures presented at the THIRD INTERNATIONAL SYMPOSIUM ON CAROTENOIDS OTHER THAN VITAMIN A held at Cluj, Romania 4-7 September 1972 LONDON BUTTERWORTHS ENGLAND: BUTTER WORTH & CO. (PUBLISHERS) LTD. LONDON: 88 Kjngsway, WC2B 6AB AUSTRALIA: BUTTERWORTHS PTY. LTD. SYDNEY: 586 Pacific Highway, Chatswood, NSW 2067 MELBOURNE: 343 Little Collins Street, 3000 BRISBANE: 240 Queen Street, 4000 CANADA: BUTTERWORTH & CO. (CANADA) LTD. TORONTO: 14 Curity Avenue, 374 NEW ZEALAND: BUTTERWORTHS OF NEW ZEALAND LTD. WELLINGTON: 26-28 Waring Taylor Street, 1 SOUTH AFRICA: BUTTERWORTH & CO. (SOUTH AFRICA) (PTY) LTD. DURBAN: 152-154 Gale Street The contents of this book appear in Pure and Applied Chemistry, Vol. 35, No. 1 (1973) Suggested U.D.C. number 547-979-8(063) International Union of Pure and Applied Chemistry 1973 ISBN: 0 408 70493 4 Printed in Great Britain by Page Bros (Norwich) Ltd, Norwich ORGANIZING COMMITTEE Chairman: Vice-chairmen: C. BODEA I. PUIA G. MARCU Symposium Editor: E. NICOARA Secretary General: V. TAMAS Members: G. NEAMTU M. FLORESCU G.ILLYES CAROTENE BIOSYNTHESIS IN FUNGI B. H. D A VIES Department of Biochemistry and Agricultural Biochemistry University College of Wales, Aberystwyth ABSTRACT Studies on Neurospora crassa and mutants of Phycomyces blakesleeanus have led to a reappraisal of a number of important aspects of carotene biosynthesis. Results obtained from structural investigations, from inhibitor studies and from the use of labelled substrates with carotenogenic extracts of fungal mutants are discussed in the contexts of the stereochemistry, isomerization and dehydrogenation of phytoene, the pathway of carotene cyclization and the feedback control of the biosynthetic pathway. INTRODUCTION Studies on a number of fungi, including Neurospora crassa, Blakeslea trispora, Mucor hiemalis and, particularly, Phycomyces blakesleeanus, have figured prominently in the literature of carotenoid biosynthesis over the last twenty years. That they have done so is largely attributable to certain advantages that fungi have over many other organisms as experimental systems for studies of carotenogenesis. Their carotenoid content is relatively simple, so that investigations of their hydrocarbon carotenes are, in general, not complicated by the presence of the oxygenated xanthophylls, which are more characteristic of higher plants, algae and bacteria. The ease with which they could be cultured, and the nutrients and other culture conditions varied, meant that they were ideal organisms for many of the early and important studies which laid the foundations of our present knowledge of carotenoid biosynthesis. It is appropriate at this time to recall the contributions made to this field by the late Professor Grob who, with Schopfer1, first demonstrated the stimulation by acetate of ß-carotene (β,β-carotene) formation in P. blakesleeanus and who, using [1- 14 C]- and [2- 14 C] acetate, showed that ß-carotene is formed by M. hiemalis from repeating isoprene units 2 - 4 . Goodwin, Mackinney and Chi