BCH 380 Biochemistry Exam 2 Study Guide Lectures 13 21 Chapters 9 13 15 18 March 2015 Lecture 13 February 23 Chapter 9 Hemoglobin What are the 2 Oxygen Carriers in the Body 1 Hemoglobin Hemoglobin Hb carries O2 from lungs to tissue Hb O2 and CO2 and H from tissues to lungs HB CO2 H Not a true enzyme but has allosteric behaviors in the regulation of O2 carrying capacity Tetramer alpha2beta2 Bind 4 O2 Found in RBCs Gives up 66 of O2 Fetal Hb has a higher affinity for O2 than maternal Hb 2 Myoglobin Monomer Bind I O2 Found only in muscles Gives up 7 of O2 How does oxygen binding to hemoglobin effect kinetic curve and relate to release o Mb displays classical M M kinetics hyperbolic o Hb displays classical Allosteric Kinetics sigmoidal Where is oxygen bound in heme and how does binding of one oxygen influence structure and cooperative binding of more oxygen o Binding of oxygen moves the iron atom into the plane of the heme Low oxygen affinity T state High Oxygen Affinity O2 bound to heme R state 1 2 3 BPG binds to deoxyhemoglobin stabilized T state of O2 carrier 2 Molecular symmetry and positive polarity form salt bridges with lysine and histideine residues in the 4 subunits of hemoglobin Fetal Hb has a higher affinity for O2 than maternal Hb What are the allosteric regulators positive and negative of oxygen affinity in hemoglobin and how do they work Bohr effect The Bohr Effect The effect of pH and CO2 on O2 binding to Hb Increase CO2 Decrease pH proteins release O2 load Decrease CO2 Increase pH Hb picks up more O2 CO2 reacts with water to form H2CO3 Lecture 14 February 25 Chapter 10 Carbohydrates Role and structures of carbohydrates o Single most abundant form of biomolecule found in nature o Have the general molecular formula of CH2O n where n 3 or higher o Function cellularly forms of energy structural linkers with other biomolecules glycolipids RNA DNA glycoproteins o Serve as recognition molecules between cell types and cell structures o Carbs have one or more asymmetric chiral center o As the monomer they can exist in either a linear of cyclized form o They can form polymers via a glycosidic bond o Readily form H bonds to water or other molecules of importance in their environment Nomenclature aldose Ketose Hexose Triose etc Numbering A sugar that meets the CH2O n formula ends in ose and can be named by number of carbon atoms e g triose tetrose pentose hexose o The name can also include whether it is an aldose or ketose e g aldohexose ketopentose etc o Monosaccharide individual sugar unit with formula CH2O n 2 Classes 1 Aldoses contains an aldehyde at least one chiral center 2 Ketoses has a ketone functional group at least one chiral center o Disaccharide tri tetra etc from 2 10 units o Oligosaccharide greater than 10 o Polysaccharide larger polymer 10 s to 1000 s may be linear or branched MW of than 1x106 possible Know structures of Glucose and Fructose both linear Fischer form and Haworth Identify the anomeric carbon and know the alpha and beta ring structures o Anomers a new chiral center formed upon cyclization Designated as a or b depending on direction of new alcohol functionality alpha is down and beta is up Know isomer nomenclature Epimer Diastereomer Constitutional isomer Anomer Enantiomer o Enantiomer non superimposable mirror images either D or L using a fishcher projection By convention for monosaccharides with 2 or more asymmetric centers diastereomers the prefix D or L refers to the configuration of the carbon with the highest the asymmetric carbon furthest from the carbonyl carbon o Diastereomer multiple chiral centers not mirror images o Epimer diastereomers that differ at only one chiral center Epimers are a kind of diastereomer Linkages know what they are and how to draw them and resulting polymers i e Glycogen alpha 1 4 linkages with alpha 1 6 branches o When put two monomers together glycosidic bond D glucose alpha 1 6 D Glucose o Sugar Polymers Can be broken down into three classes 1 Unmodified glucose polymers o i alpha linked 1 4 linkage causes a KINK Many H bonds are made between the Glc and water ii beta linked i e cellulose most abundant nature polymer in world forms long flat stackable polymers i e chitin antiparallel and a mix otherwise similar to cellulose Aliginate can be alpha or beta or both 2 Modified glucose polymers 3 Mixed sugar polymers o Polysaccharides allow many Glc molecules to be stored in a cell with little effect on osmolarity osmolarity depends on of molecules not their size Branching helps present many non reducing ends on the many chains in the branched polymer to enzymes that break down polysaccharides so we can quickly produce glucose when we need it Know the difference between proteoglycan and a glycoprotein and their functions o Glycoproteins Covalently linked oligosaccharide and proteins Main function and usually mass comes from the protein Mainly proteins with a little carb Most secreted proteins are glycosylated Include structural proteins enzymes membrane receptors transport proteins immunoglobulins Bacteria don t do this Can be O linked often found in suface glycoproteins and mucins to Ser Thr or hydroxylysine N acetylglucosamine although Mann Gal Xyl also N Linked linked to mannose triad to Asn N acetylgalactosamine and rich in sialic acids o Proteoglycan mainly carb with some protein Example cartilage Lecture 15 March 2 Chapter 11 Lipids Roles for fatty acids and lipids o Lipid is a generic term for any biological molecule that has low water solubility o Many biomolecules can fall into this category so the exact definition is somewhat hazy Generally regarded as the categories described under Structures in slide 1 o Generally the structures we are describing as lipids have numerous reduced carbons in large chains This gives them significant upside with regard to oxidation potential o Lipids can be classified as either hydrophobic or amphipathic has both polar and nonpolar parts o At physiological pH the carboxyl group is ionized o Most fatty acids have an even number of carbons because they are made from the two carbon acetyl CoA precursor o Most of the biologically relevant fatty acids fall in the number range of C 12 C24 o Fatty acids can be considered saturated all carbon carbon single bonds or unsaturated one or more double bonds o Fatty acids that contain one double bond are called monounsaturated o fatty acids or MUFA s MUFA s considered good in diet Mediterranean Diet o Fatty acids that contain more than one