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Hemoglobin & Myoglobin

Electronegative they donate electrons to keep fe in

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Unformatted text preview: oxygen to bound and the delievery - amino acids do not bind oxygen taht why you need this prosethetic group 2/8 and 2/11/13 MCB 2000 Lecture 6 .#4$213)1* 012/51/23&* 9"31/2"0*$9*7"#"* =2$1$4$247-2()*2()%* !-;2$47$'(5L*4&3)32* X(12$%")0*42":")1*@"NQ*1$*@"KQ*172$/%7*17"(2* "&"512$)*;$)31()%*53435(1-*[email protected]"NQ*'();0*$F-%")* 2":"20('&-L*@"KQ*53)*)$1E* 012/51/2"* 2/8 and 2/11/13 Heme - proptoporphyrin ring stucture - in the center is a Fe (Iron) - bonded to 4 nitgoren - any trasnsition metal under go oxidation reduction - that means they are very reactive - keep Iron in the +2 state in order to bind oxygen Nitrogen electronegative - they donate electrons to keep Fe in the +2 state - this molecule v ery hydrophobic - in the hemogolbin and mygolbin - what kind of molecule will surround?-- non polar r esidients- in hydrophobic clef some exposed to the surface MCB 2000 Lecture 6 !"#$%&$'()*G12/51/2"*R/1$2(3&* http://www.rpc.msoe.edu/cbm/jmol/1a3n.php http://higheredbcs.wiley.com/legacy/college/boyer/0471661791/structure/HbMb/hb mb.htm Planar stucutre - Iron hangs out. look at the display heme group histidines - in addition to the 4 nigrogen there are 2 histidines molecules - one on the top and one on the bottom - 4 nitrogen and 2 hisitindes - this is important for oxygen binding 2/8 and 2/11/13 MCB 2000 Lecture 6 Hemoglobin Function Hb must bind oxygen in lungs and release it in capillaries When the first oxygen binds to Fe in heme, Fe is drawn into the plane of the porphyrin ring. This disrupts key noncovalent interactions that cause a change in conformation. 2/8 and 2/11/13 MCB 2000 Lecture 6 In the absence of oxygen - Fe hanging below then oxgeyn binds the the Fe pushed into the plane of the ring - binding of oxygen shifts the movement of Fe - the histidine is pulled along with it - Histidine part of a helix After you break the bonds - new ones will form - change conformation - binding of new - this is tied into the function of the moecule Y(02/41($)*$9*)$)5$:3&")1*()1"2351($)0*$)* '();()%*$F-%")* !"#$%#&'()"#*+#,-.#,/0-1'2# 3+4-"# 5+""#+6#'(*-789*'+("# &-*:--(#,#8()#;#0-1'9-"<# =< >81*#&7')?-#&-*:--(# !"@AB#8()#;'"=BC#'"# &7+D-(<# %< >81*#&7')?-#&-*:--(# 5E"BF#8()#;'"=BC#'"# )'"[email protected]*-)<# H< ;/&+()#&-*:--(#I81AJ# 8()#KE7=BL#81"+# )'"[email protected]*-)# 2/8 and 2/11/13 MCB 2000 Lecture 6 In deoxy state Fe out of the ring - the helix (F and H) form electrostatic interaction. D - aspartic acid - forms a s alt bridge = electorstatic interaction - salt bridge between Lysine (K) with Histidine 146 - Histidine forming 2 electrostatic interaction - and the 3rd hydrogen bond between Val and hydroxyl group of Try 2. 1. 3. F-helix H-helix Binding of oxygen induces a 15 degree shift along the interface. 1...
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