&quot;D和L-丙氨酸宇称破缺能差正负&quot;的争论

doi:10.3866/PKU.WHXB20021002

CORC > 北京大学 > 化学与分子工程学院

	"D和L-丙氨酸宇称破缺能差正负"的争论; A Debate on the Parity-Violating Energy Difference of D- and L-Alanine
	王文清 ; 孙琳 ; 闵玮 ; 王哲明
刊名	物理化学学报
	2002
关键词	宇称破缺能差 D-和L-丙氨酸二面角二级相变 X射线四圆单晶衍射 Parity-violating energy difference D- and L-alanine Dihedral angle Second order phase transition X-ray diffraction parity-violating energy difference D- and L-alanine dihedral angle second order phase transition X-ray difftaction
DOI	10.3866/PKU.WHXB20021002
英文摘要	在宇宙开始大爆炸的时候,电荷变号与镜象反射共轭(CP)是对称的.但现在我们的宇宙绝大部分是正物质核子和电子等组成的,所以我们的宇宙是不对称的.D和L-丙氨酸通常称为对映体(enantiomer),实际上它们并不是由正、反粒子组成的真正的对映体,而是空间反演的,即x→-x,y→-y,z→-z的非对映异构体(diastereoisomer),所以D-和L-丙氨酸是不对称的,两者间有能量的差别.自然界的力只有弱力是宇称不守恒的.在分子物理中,电弱力宇称不守恒是导致D-和L-丙氨酸能差的根源.所有以前的研究都认为L型丙氨酸比D型稳定.但是,最近以Quack[9]和Schwerdtfeger[11]为首的理论物理学家计算了L-丙氨酸在气相和溶液两种状态下,宇称破缺能差与分子构象的关系,提出"D-和L-丙氨酸究竟哪一个稳定"的质疑.由于气相和液相中两面角较难测定,我们用X射线四圆单晶衍射法,测定了270 K和250 K D和L-丙氨酸的O(1)O(2)C(1)C(2)H(4)的原子坐标,算出了二面角,按照Quack[9的MC-LR方法,D-和L-丙氨酸宇称破缺能差为1.2×10-19Hartree,相当于3.3×10-18eV/分子或3.2×10-16KJ@mol-1,从而得出D-丙氨酸能态高于L-丙氨酸的结论.; The chiral purity of biochemical monomers-only L-amino acids are present in proteins and D-sugars in the DNA and RNA of living organisms-is today accepted as an absolute necessity for the existence of life. All previous studies on amino acids reported the naturally occurring L-form to be stabilized by weak neutral currents. Two recent papers dealing with electroweak quantum calculations of the parity-violating energy shifts of alanine in gaseous phase and in solution have defied this long held belief. The parity-violating energy difference (PVED) of D-and L-alanine was undertaken as a function of the dihedral angle theta of the carboxylate plane with respect to the C.-H. plane. Dihedral angles was calculated from the atomic coordinates of O(1) O(2) C(1) C(2) H(1) of D-and L-alanine under the temperature dependence of X-ray diffraction data. According to Quack's theoretical results by means of highest level ab initio studies (MC-LR), the Delta E-PV value is 1. 2 x 10(-19) Hartree (3. 3 x 10(-18) eV/ molecule), namely L-alanine is more stable than D-alanine. The present paper proved definitely that in the single crystal state L-alanine is lower in energy than D-alanine both by X-ray diffraction data and the differential scanning calorimetry.; 国家高技术研究发展计划(863计划); 秦惠君-李政道大学生研究基金; http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000178709800002&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701 ; SCI(E); 中文核心期刊要目总览(PKU); 中国科技核心期刊(ISTIC); 中国科学引文数据库(CSCD); 1; 10; 871-877; 18
语种	中文
内容类型	期刊论文
源URL	[http://ir.pku.edu.cn/handle/20.500.11897/208038]
专题	化学与分子工程学院
推荐引用方式 GB/T 7714	王文清,孙琳,闵玮,等. "D和L-丙氨酸宇称破缺能差正负"的争论, A Debate on the Parity-Violating Energy Difference of D- and L-Alanine[J]. 物理化学学报,2002.
APA	王文清,孙琳,闵玮,&王哲明.(2002)."D和L-丙氨酸宇称破缺能差正负"的争论.物理化学学报.
MLA	王文清,et al.""D和L-丙氨酸宇称破缺能差正负"的争论".物理化学学报 (2002).