HNF 462 1st Edition Lecture 10Outline of Last LectureI. Structure and Food SourcesII. Digestion and AbsorptionIII. TransportIV. Storage and ExcretionV. FunctionsVI. DeficiencyVII. Schilling TestOutline of Current LectureI. StructureII. AbsorptionIII. MetabolismIV. BioavailabilityV. TransportVI. Storage and ExcretionVII. Functionsa. Coenzymei. Schiff Baseb. Transaminationc. Decarboxylationd. Deaminatione. Synthetic ReactionsVIII. DeficiencyCurrent Lecture: Vitamin B61. StructureThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.a. 3 Free Forms: Pyridoxine (PN), Pyridoxal (PL), and Pyridoxamine (PM)b. 3 Phorphorylated Forms: Pyridoxine Phosphate (PNP), Pyridoxal Phosphate (PLP),and Pyridoxamine Phosphate (PMP) 2. Absorptiona. Intestinal: Passive diffusion of free forms; some absorption of phosphorylated forms at high concentrationsb. Cellular: Passive diffusion into/out of the cell; unphosphorylated forms go in and out of the cell freely3. Metabolisma. Liver is main organ of B6 metabolismb. Free forms are phosphorylated by kinasec. Oxidase oxides PNP and PMP to PLP (biologically active form)4. Bioavailabilitya. High bioavailability, but decreases when B6 is exposed to heat and processing5. Transport: In blooda. Main form as PLPb. Bound to albuminc. Bound to hemoglobin in red blood cellsd. PLP must be converted to PL (by alkaline phosphatase) to be taken up by other tissues6. Storage and Excretiona. Storage: In muscle as PLP bound to glycogen phosphorylase and bound to proteins that protect B6 from phosphataseb. Excretion: via urine7. Functionsa. Coenzyme for >100 enzymesi. Mostly amino acid metabolismii. Formation of Schiff Base: double bond between the nitrogen of an amino acid and the carbon of PLP. At the same time the N is also bonded to a hydrocarbon moleculeb. Transamination: alanine donates amino group to an alpha-keto acid (usually alpha-ketoglutarate)i. Alanine Pyruvateii. Alpha-ketoglutarate glutamate (an amino acid)iii. Transferring of amino acids into TCA cycle relies on B6iv. Alanine Cycle: 1. In muscle: Glucose Pyruvate Alanine (by transamination)2. In liver: Alanine Glucosec. Decarboxylation: Important for proper neurological functions (does not convert NAD to NADH like thiamin-related decarboxylation reactions)d. Deamination: Similar to transamination, but instead of transferring an amine group, it gets rid of ite. Synthesis Reactionsi. Heme Formationii. Niacin Formation (from tryptophan)8. Deficiencya. Hypochromic Microcytic Anemia: RBCs lighter in color and smaller than normalb. Hyperhomocysteinemia (homocysteine cysteine uses PLP-dependent
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