HNF 462 1ST Edition Lecture 7Outline of Last Lecture I. Food Sources and Digestiona. CoAII. Absorption, Transport, and ExcretionIII. FunctionsIV. Deficiency and Measurementsa. AIOutline of Current LectureI. Food Sources and DigestionII. AbsorptionIII. TransportIV. Functionsa. Coenzymeb. Gene Expressionc. Protein ModificationV. ExcretionVI. DeficiencyCurrent Lecture: Biotin1. Food Sources and DigestionThese 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. Wide distribution of food sourcesi. Bound to protein (usually lysine)b. Made by bacteria in colon2. Absorptiona. Must be released from protein/amino acids by biotinidaseb. Into the Intestine: SMVT transporter. Dietary biotin absorbed in proximal small intestine; bacterial biotin absorbed in proximal/midtransverse colonc. Into the blood: Na-independent transporter3. Transporta. In the blood: primarily in its free form, but some is bound to globulins or biotinidasei. Biotinidase has 2 binding sites and is secreted by the liver4. Functionsa. Coenzyme: adds an activated carboxyl group (COO-) to substratei. Pyruvate Carboxylaseii. Acetyl CoA Carboxylaseiii. Propionyl CoA Carboxylaseiv. B-Methylcrotonyl CoA Carboxylaseb. Regulation of Gene Expressioni. Overview: gene regulation occurs at 4 levels1. Transcriptional2. Epigenetic3. Translational4. Post-Translationalii. Biotinylation of histones affects the accessibility of the DNA transcriptional factors c. (Non-Histone) Protein Biotinylation5. Excretiona. Must be released as free biotin before being excreted through urine6. Deficiencya. Symptoms include lethargy, nausea, and dermatitisb. At Risk for Deficiency: raw egg consumption (avidin), pregnancy, genetic mutations of biotinidase, and alcoholicsc. Note: No
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