Biophysics of Electron Transfer and Molecular Bioelectronics ELECTRONICS AND BIOTECHNOLOGY ADVANCED (EL.B.A.) FORUM SERIES Volume 1 FROM NEURAL NETWORKS AND BIOMOLECULAR ENGINEERING TO BIOELECTRONICS Edited by Claudio Nicolini Volume 2 MOLECULAR MANUFACTURING Edited by Claudio Nicolini Volume 3 BIOPHYSICS OF ELECTRON TRANSFER AND MOLECULAR BIOELECTRONICS Edited by Claudio Nicolini A Continuation Order Plan is available for this series. A continuation order will bring delivery of each new volume immediately upon publication. Volumes are billed only upon actual shipment. For further information please contact the publisher. Biophysics of Electron Transfer and Molecular Bioelectronics Edited by Claudio Nicolini Institute ofB iophysics University ofGenoa Genoa, Italy Springer Science+Business Media, LLC Library of Congress Cataloging-1n-Publicat1on Data 81ophysics of electron transfer and molecular b1oelectronics 1 edited by Claudio N1col1ni. p. cm. -- CElectronics and biotechnology advanced CEL.B.A. 1 forum series , v. 31 Includes b1bl1ographical references and index. ISBN 978-1-4757-9518-9 ISBN 978-1-4757-9516-5 (eBook) DOI 10.1007/978-1-4757-9516-5 1. Metalloproteins. 2. Charge exchange. 3. Molecular electronics. I. Nicolinl. Claudio A. I!. Ser1es, Electronics and biotechnology advanced foum ser1es , v. 3. RC552.M46856 1998 572 · .43--dc21 98-31320 CIP Proceedings of the 1997 International Workshop on Biophysics of Electron Transfer: Fundamental Aspects and Applications, held October 8 ~ I 0, 1997, in Bressanone, ltaly ISBN 978-1-4757-9518-9 © 1998 Springer Science+Business Media New York Originally published by Plenum Press, New York in 1998 Softcover reprint of the bardeover 1st edition 1998 http://www. plenum.com 10987654321 All rights reserved No part of this book may be reproduced, stored in a retrieval system, or Iransmitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recording, or otherwise, without written permission from the Publisher PREFACE The present volume is a continuation ofthe EL.B.A. Forum Series which was initiated in the spring of 1992 in Marciana Marina (Italy), with the first volume entitled From Neural Networks and Biomolecu/ar Engineering to Bioelectronics published by Plenum Press in 1995. Bioelectronics-miginally introduced in April, 1987, at a symposium hosted by CIREF, a research consortium among leading high tech industries in Novara (Italy)---was later defined in two successive consensus reports at the first (Bruxelles, 1991) and second (Frankfurt, 1994) European Union Workshops on this widely interdisciplinary field, as "the use ofbiological materials and biological architectures for information processing and sens ing systems and devices down to molecular Ievel." lt is worth noting that these workshops gave birth to the first European research program on "lnterfacing Biology with Electronics" during 1996-1999, following the !arge Programma Nazionale Ricerca on "Technologies for Bioelectronics" launched by the ltalian Ministry ofUniversities and Research in 1990. In autumn, 1996, with the second volume, entitledMolecular Manufacturing, the em phasis was placed on the ernerging parallel area of nanotechnology, independently initiated in Palo Alto, Zurich, Genova, Mainz, and Tokyo by various groups (i.e., IBM, Xerox, Polo Nazionale Bioelettronica, Max Planck Institutes), universities (i.e., Stanford, Genova, Rice, Tokyo), and organizations (i.e., Foresight, Erato, Fondazione EL.B.A., Frontiers Research, MITI) of different sizes, scopes, and latitudes. The present third volume ofthe series highlights the various aspects ofthe biophysics of electron transfer which has been ernerging as an independent branch of research. This vol ume appears at a crucial moment, when significant progress is being made in this field, and when technologies derived from it are being recognized as critical for the development ofbio technology, electronics, and material sciences. The significant roJe, ofthe Fondazione EL.B.A., the Istituto Cultura Trentina, and the Istituto Nazionale Biostruttura e Biosistemi in the organization ofthis sixth course ofthe Na tional School ofBiophysics in Bressanone, ltaly, October 8-10 1997, with the cooperation of UNESCO and the ltalian Society ofBiophysics, are duly acknowledged as weil as forattract ing and supporting (within the framework of Copernicus project number ERBIC l5CT9608l 0 sponsored by the European Union) top Ievel scientists for the XIV EL. B.A. Forum summarized in this volume and part ofthis course. Polo Nazionale Bioelettronica must be acknowledged for bringing to light this series and the enormous industrial potential of electron transfer in biopolymers. I would like to express my gratitude particularly to Mr. Fabrizio Nozza and Andrea Rossi ofthe Fondazione EL.B.A. Claudio Nicolini Member of the National Science and Technology Council President ofthe Fondazione EL.B.A. V CONTENTS Metalloprotein Engineering for New Materials, Drugs and Nanodevices ........... . C. Nicolini :n Modulation of the Electron Transport System of Oxygenic Photosynthesis . . . . . . . . . . G. Forti and G. Finazzi Electron Transfer in Mitochondrial Steroid Hydroxylating Cytochrome P450 Systems: RoJe of Adrenodoxin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 R. Bernhardt Preparation, Structural Characterization and Functional Coupling of Tethered Membranes to Solid Substrates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 W. Knoll, N. Bunjes, M. Denyer. C. Heibel, M. Matsuzawa, R. Naumann, A. Offenhäusser, J. Rühe, E.-K. Schmidt, A. Sinner, and C. Sprößler Targeted Expression of Mammalian Cytochromes P450scc and P4502b4 in Yeast Saccharomvces cerevisiae . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 M. A. Eldarov, V. E. Sidorovich, G. E. Pozmogova, and K. G. Skryabin The Molecular Role of the Pufx Protein in Bacterial Photosynthetic Electron Transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I 03 F. Francia, P. Turina, B. A. Melandri, and G. Venturoli Single Electron and Quantum Phenomena in Ultra Small Particles . . . . . . . . . . . . . . . . I 17 V. Erokhin, S. Carrara, and C. Nicolini Electron Correlation in Quantum Molecular Biophysics: The Case Study of Hemocyanin ....................................................... 139 P. Fariselli and R. Casadio Electron Transfer Reactions in Multicopper Oxidases ........................... 161 L. Calabrese The Optical Biosensor Study of Protein-Protein Interactions within Cytochromcs P450 Containing Monooxygenase Systems ............................... 173 A. I. Archakov and Y. D. Ivanov Index ................................................................. 195 VII METALLOPROTEIN ENGINEERING FOR NEW MATERIALS, DRUGS AND NANODEVICES Claudio Nicolini Istituto di Biofisica, Universita di Genova Corso Europa 30, 16132 Genova Italy Polo Nazianale Bioelettronica, Via A. Moro 17, 57030 Marciana Marina (LI), Italy Fondazione Elba Via del Babuino 181, 00187 Roma Italy INTRODUCTION The purpose of this chapter is to provide an overview of present efforts on the engineering thin films of of various metalloproteins, likewise P450 and C cytochromes and Photosynthetic Reaction Center {RC), from ab initio considerations on the individual proteins in solution up to the assembly and characterization of monolayers and multilayers. Over the years metalloproteins, namely P450, C and Photosynthetic Reaction Centers, have become the proteins of choice among the many currently under study in my laboratories towards the implementation of drugs, materials and devices for numerous industrial applications. It should be noted that several molecular manipulation techniques have been recently introduced which could be utilized in order to optimize the properties of the above cytochromes in a wide range of applications, namely: self-assembly (Morgan et al., 1992; Hoffinann et al., 1992; Nicolini et al, 1995); Langmuir-Blodgett/Langmuir-Shaeffer techniques and their modifications (Nicolini et al., 1993; Antolini et al 1995; Nicolini, 1996b, 1997), including utilisation of reverse Iipid micelies (Erokhin et al., 1994) and derivatization (Riccio et al, 1996) to form ordered thin protein films; site-directed chernical modifications complementing the above two techniques (Bernhardt et al, this volume; Paskievitch et al., 1996). The choice of metalloproteins as the most plausible materials to be used in bioelectronics is determined by several of their inherent well-documented properties, of which the most important is that the meta! sites present in those proteins are redox centers across which electron transfer occurs along highly selective multidirectional pathways (Nicolini, 1996a); this is not the case for low-molecular-weight electron carriers in inorganic materials such as silicon, that are unidirectional and more uniformly (i.e., less selectively) reactive with respect to electron Bwphysics of Electron Transfer and Molecu/ar Bwelectronics Edited by C. Nicolini, Plenum Press, New York, 1998 transfer. These pathways are considered later in the chapter. Other considerations are as follows for these classes of proteins: metal sites are weil characterized by a number of spectral methods, so useful structural and mechanistic information can be obtained using relatively inexpensive techniques; • as a result of genetic engineering efforts, the genes for most of these systems are available and can be expressed in large quantities in yeast or E. coli (Eldarov et al., 1996). have well-studied biophysical, biochemical and enzymatic properties since they have served as routine objects for many types of investigations; have highly asymmetric distributions of electrostatic fields araund them. Same also have asymmetric distribution of hydrophilic/hydrophobic amino acid residues over their surfaces. Both of the two factors can be used for controlled association of these proteins into supramolecular structures like thin films suitable for macroscopic characterization and/or direct industrial applications. from X-ray or NMR experiments, three-dimensional structures are known for most of them, which are good starting points for designing or improving their properties, stabilities and electron-transfer characteristics in several applications; for few others, likewise P450 sec and P450 B24, modeling by homology might be the raute, until X ray crystallography and NMR experiments still in progress will provide the needed informations. METALLOPROTEINS SYSTEMS Cytochrome C Cytochrome Cis a small ["13 kDa, 104 amino-acids] soluble heme protein, which serves to shuttle electrons between cytochrome reductase and cytochrome oxidase in the respiratory electron-transfer chain. The high-resolution three dimensional structure of horse heart Cytochrome C has been recently elucidated. The polypeptide chain is folded into a roughly globular shape within which a heme packet is formed. The heme group, covalently linked to the polypeptide chain via condensation of its vinyl peripheral substituents with cysteine in the 14 and 17 positions, is nearly completely buried within the surrounding protein matrix, but forms a number of hydrogen bonds with nearby polar main-chain and side-chain groups and therefore occupies a clearly hydrophilic local environment. Only four atoms of one edge of the protoporphyrin IX heme prosthetic group are exposed to solvent (CMC, CAC, CBC, CMD carbons), encircled by positively charged Arg and Lys. Two internally bound water molecules seem to play apart in electron transfer. One internally bound water molecule (Watl25) mediates a charged interaction between the heme propionate 01A and the guanidinium group of Arg-38. The other water molecule (Watl12) is inside the protein molecule, centrally buried next to the heme group. Horse Cytochrome C has two surface tyrosines, in contact with the solvent, and two that are buried. One of the latter, Tyr-67, is involved in H-bond donation to the sulphur atom of Met-80 and a water molecule, which is in turn H-bonded to Thr-78. These are expected to be relatively weak H-bonds. The other buried tyrosine, Tyr-48, donates and H-bond to a negatively charged heme propionate group, which is expected to produce a strong interaction. The pronounced evolutionary conservatism of aromaticity araund the heme group suggests that these rings have an important roJe. Photosynthetic Reaction Centre Reaction Center from Rhodobactei. Sphaeroides. is a !arge (100 kDa) transmembrane protein made of 3 subunits (L, M, and H) and is involved into the first stage of photosynthesis 2 providing photoinduced transmembrane electron transfer (I 00% quantum yield) in photosynthetic bacteria (Branden and Tooze, 1991 ). Crystal structure of this protein has been reported in the Iiterature (Allen et al., I987; Yeates et al., I987). Electron transfer chain formed by a dimer ofBacteriochlorophyll (Bchl2), Bacteriopheophytin (Bphe), and 2 Quinones (Qa and Qb) is shown in figure I along with the schematic subunit structure. In natural conditions Bchl2, primary donor in the RC electron transfer chain, is reduced by a multiheme cytochrome attached at the periplasmatic side of the protein; cytochrome is lost during the extraction from the membrane (Branden and Tooze, 1991). The RC solution here used contains protein molecules surrounded, in the hydrophobic region, by the detergent used for the extraction, i.e. spreading solution is made oftwo components. P450scc Cytochrome There is no data on seif-exehange in cytochromes P450. This is related to the fact that is, unlike other cytochromes, a complex enzymatic system involving other coenzymes (Adx and AdR) in which the electron transfer must proceed in concert with other functions like substrate binding and oxygen activation, and is performed with the help of cofactors - the iron-sulphur protein, reductase, and, in some cases, cytochrome B5 (Porter and Coon, I99I ). Also, it follows from its 3D structure (Figure I) that there is no way of bringing its possible inner electron transfer pathways close to those of another P450 molecule unless its conformation dramatically changes. Accordingly, the estimated seif-exehange rate for cytochrome P450 is nearly zero. The structure of this protein has not yet been determined by X-ray crystallography, so sequence homology modelling has to be applied to provide a model for this structure. Such a model has been developed at this Institute, but a model is present also in the Protein Data Bank (Vijayakumar and Salerno, I992). The key feature of cytochrome P450-catalysed reactions is the transfer of electrons from NAD(P)H to either NADPH-cytochrome P-450 reductase in the microsomal system (P450d) or a ferredoxin reductase and a non-haem iron protein (in the case Figure I. Proposed model for the heme environment of the P450scc. The heme is attached to Cys423, and its carboxyls interact with Arg357 and Arg421. 3