UPPSALA charged amino acids R group has a charge at physiological pH (7. 4). pk of the charged groups vary H3N'-c-C HN° H3N'-C N'-c CH CH CH2 H CH2 CH2 CH2 NH3 C NH2 NH2 ASPARTIC ACID GLUTAMIC ACID ARGININE HISTIDINE (Asp) (G|u) ( Lys) (Arg) (His carboxyl amino guanidino imidazole group group group grouggroup, sometimes charged ost often classified as a polar amino acid
charged amino acids - R group has a charge at physiological pH (7.4). pK of the charged groups vary carboxyl group carboxyl group amino group guanidinio group imidazole group, sometimes charged Most often classified as a polar amino acid
§3蛋白质结构的组织与类型 一级结构 二级结构 三级结构 四级结构 AHFHD YHFH AHYHTK FHDHF v四 Amino acid Alpha helices& Arrangement Packing of several sequence. Beta sheets of secondary polypeptide chains Loops elements in 3D space 结构生物学家感兴趣的是蛋白质的高级结构
一级结构 二级结构 三级结构 四级结构 Amino acid sequence. Alpha helices & Beta sheets, Loops. Arrangement of secondary elements in 3D space. Packing of several polypeptide chains. 结构生物学家感兴趣的是蛋白质的高级结构 §3 蛋白质结构的组织与类型
Peptide units(肽键) H A peptide is a set of Ha+N covalently bonded amino acids The covalent bond is usually referred as H peptide bond +aa3 H. Rl H C—N H etc H Pe H
Peptide units (肽键） A peptide is a set of covalently bonded amino acids. The covalent bond is usually referred as peptide bond
Biochemist's peptide unit -from n to C all main chain atoms within the unit lie in the same residue 120.5° 1235° Peptide bond 116° 11110 1195 1185° (a) side claIn 10 Amide H H trans-Peptide group OH Structural biologist's peptide unit- from Ca to next Ca-all amino group carboxyl group main chain atoms within the unit lie in a plane (6) peptide bond H H H C H H H RI C1999 GARLAND PUBLISHING INC A emler ef the Taub Francis Growp peptide bond I9 GARLAND PUBLISHING IN
Biochemist’s peptide unit –from N to C – all main chain atoms within the unit lie in the same residue Structural biologist’s peptide unit – from Ca to next Ca - all main chain atoms within the unit lie in a plane
Peptide torsion angles N phi psi omega H R phi Angles phi()N-cCa H Angle psi (y) CaCO Angle omega(O)C-N peptide plane 919 GARLAND PUBLISHING INC A member of the Tayior Francis Group
– Angles phi (f) N-Ca – Angle psi (y) Ca-CO – Angle omega (w) C-N