Biophysics An Introduction Rodney M. J. Cotterill D anish Technica l Universit y , Denm a rk Biophysics An Introduction Biophysics An Introduction Rodney M. J. Cotterill D anish Technica l Universit y , Denm a rk Copyright © 2002 by Rodney M. J. Cotterill Published by John Wiley & Sons Ltd, BaffinsLane,Chichester, WestSussexPO191UD,England National01243779777 I nt ernat inoal (+44) 1243 779777 e-mail(forordersandcustomerserviceenquiries): [email protected] Visit our Home Page on http://www.wiley.co.uk orhttp://www.wiley.com Allrightsreserved.Nopartofthispublicationmaybereproduced,storedinaretrievalsystem,or transmitted,inanyformorbyanymeans,electronic,mechanical,photocopying,recording,scanning orotherwise,exceptunderthetermsoftheCopyright,DesignsandPatentsAct1988orundertheterms ofalicenceissuedbytheCopyrightLicensingAgency,90TottenhamCourtRoad,London,UKW1P9 HE,withoutthepermissioninwritingofthepublisher. Ot her Wiley Editorial Of f ices John Wiley & Sons, Inc., 605 Third Avenue, NewYork,NY10158-0012,USA Wiley-VCH VerlagGmbH,Pappelallee3, D-69469Weinheim,Germany John Wiley & Sons (Australia) Ltd, 33 Park Road, Milton, Queensland4064,Australia JohnWiley&Sons(Asia)PteLtd,2ClementiLoop#02-01, JinXingDistripark,Singapore0512 JohnWiley&Sons(Canada)Ltd,22WorcesterRoad, Rexdale,OntarioM9W1L1,Canada LibraryofCongressCataloging-in-PublicationData Cotterill,Rodney,1933– Biophysics:anintroduction/RodneyCotterill. p.cm. Includesbibliographicalreferencesandindex. ISBN 0–471–48537–3(acid-free paper)—ISBN 0–471–48538–1(pbk.:acid-freepaper) 1.Biophysics. I.Title. QH505C642002 571.4—dc21 2002069134 BritishLibraryCataloguinginPublicationData AcataloguerecordforthisbookisavailablefromtheBritishLibrary ISBN 0471-485373(Hardback)0-471485381(Paperback) Typesetin10.5/13ptTimesbyKolamInformationServicesPvt.Ltd,Pondicherry,India PrintedandboundinGreatBritainbyTJInternationalLtd,Padstow,Cornwall Thisbookisprintedonacid-freepaperresponsiblymanufacturedfromsustainableforestry,inwhichat leasttwotreesareplantedforeachoneusedforpaperproduction. Fo r m y t ea ch er, Herbert C . D a w, and f o r m y b iophy sics students – past, present and future Contents Preface xi 1 Introduction 1 Exercises 6 Further reading 6 2ChemicalBinding 7 2.1 Quantum Mechanics 7 2.2 Pauli Exclusion Principle 9 2.3 Ionization Energy, Electron Affinityand ChemicalBinding 10 2.4 Electronegativityand StrongBonds 15 2.5 SecondaryBonds 21 Exercises 22 Further reading 22 3Energies, Forces and Bonds 23 3.1 InteratomicPotentialsfor StrongBonds 23 3.2 InteratomicPotentialsfor Weak Bonds 29 3.3 Non-centralForces 32 3.4 Bond Energies 33 3.5 SpringConstants 39 Exercises 40 Further reading 41 4Rates of Reaction 43 4.1 FreeEnergy 43 4.2 InternalEnergy 45 4.3 Thermodynamics and Statistical Mechanics 46 4.4 Reaction Kinetics 55 4.5 Water, Acids, Bases and Aqueous Reactions 59 4.6 Radiation Energy 65 Exercises 67 Further reading 68