Conversion of Amino Acids - Biochemistry - Lecture Slides, Slides of Biochemistry

Download Conversion of Amino Acids - Biochemistry - Lecture Slides and more Slides Biochemistry in PDF only on Docsity! Conversion of Amino Acids to Specialized Products Heme purines pyrimidines hormones neurotransmitters biologically active peptides Docsity.com Formation of glycine conjugates Benzoate CoASH AMP + PP. ™“S—CoA Benzoyl-CoA Glycine CoASH Hippurate Has eo Figure 33-1. Hippurate biosynthesis. Docsity.com Structures of natural polyamines Spermidine and spermine function in diverse physiologic processes that share as a common thread a close relationship to cell proliferation and growth. The fact that they are polycations allows these compounds to bind to DNA and RNA and they are involved in packaging of DNA in bacteriophages. Docsity.com Biosynthesis of spermidine and spermine Addition of inhibitors of ornithine decarboxylase, the enzyme that catalyzes the initial reaction in polyamine biosynthesis, triggers overproduction of ornithine decarboxylase. (hence, the machinery that makes the protein is regulated tightly in order that a supply of the precursors to spermidine and spermine is always available). Ornithine decarboxylase has a half-life of 10 minutes. Docsity.com Catabolism of polyamines Ht HAN 2 . NNN * H,! Is Spermine O2 POLYAMINE OXIDASE ° HO2 Mit oe NH B-Aminopropionaldehyde HN i wn SPOS Oat 3 Spermidine O2 POLYAMINE OXIDASE H,02 B-Aminapropionaldehyde +N ia iN NH,* Putrescine | | NH,* + CO, Figure 33-6. Catabolism of polyamines. Structures are abbreviated to facilitate presentation. Docsity.com Biosynthesis of epinephrine and norepinephrine “OL NH,* | CH oO CHy =~ CO L-Tyrosine H, + biopterin TYROSINE HYDROXYLASE OH H, « biopterin HO NHq* | CH. og cH 6«(NG# tl Dopa PLP DOPA DECARBOXYLASE co, OH HO ___CH, Hy ° NH,* Dopamine Oz DOPAMINE ap B-OXIDASE | | Cu Vitamin C OH HO CH oe CH~ ° SNA | OH Norepinephrine S-Adenosylmethionine PHENYLETHANOL- AMINE N-METHYL- TRANSFERASE S-Adenosylhomocysteine OH HO CH, CH, CH~ ~~N~ | H,* OH ° Epinephrine Figure 33-9. Conversion of tyrosine to epinephrine and norepinephrine in neuronal and adrenal cells. (PLP, pyri- doxal phosphate.) Docsity.com Biosynthesis of creatine and creatinine Creatine is a high-energy storage compound in muscle. ATP is made from creatine phosphate by creatine kinase Docsity.com Metabolism of y-aminobutyrate coo- | H—C—NH;* o-KA L-GLUTAMATE ota DECARBOXYLASE CH, TRANSAMINASE aAA coa- L-Glutamate aati coo" ie c=o = | “THyN— CH, — CH, — CH, — COO Gre CH, yAminobutyrate ia | " iy coo CH, y-Hydroxybutyrate | {0} ee coo- PLP NAD* o-Ketoglutarate LACTATE DEHYDROGENASE INH," NADH + H* CO, SUCCINIC SEMIALDEHYDE " DEHYDROGENASE wo I H,O =NAD* NADH+H* Lo coo Succinate semialdehyde Succinate Figure 33-11. Metabolism of y-aminobutyrate. (@-KA, o-keto acids; a-AA, «-amino acids; PLP, pyridoxal phosphate.) Docsity.com Uroporphyrins and coproporphyrins A P A p im | A A A | aes Uroporphyrins were first | found in the urine, but they are not restricted to urine. A | P 5 Pp bes: Pp A Pp A Uroporphyrin | Uroporphyrin tit MP M oP P M M M Coproporphyrins were first isolated from feces, but they are also found in urine. M F P P Po oM Peay Coproporphyrin | Coproporphyrin Ill 4-3. Uroporphyrins and coproporphyrins. A (acetate); P (propionate); M (methyl) = —CHs; V (vinyl) = — Docsity.com Biosynthesis of porphobilinogen COOH COOH COOH ! | | [ CH, ALA CH, | ALA CH, ! SYNTHASE | SYNTHASE | Succinyl-CoA CH, CH, es CH, (‘active” | CoA* SH co, succinate) is c=0 C8 - - _} a H—C—NH, H—C—NH, 14 i Pyridoxal i | ; Ly____4j phosphate COOH H Glycine H—C—NH, | u-Amino-[}-ketoadipate 6-Aminolevulinate (ALA) ~ COOH COOH | COOH CH, 2H,0 | | CH, CH, } | | C=C diony an ll Il gic cH ¢ DEHYDRATASE “en cH i I SEL a CH, N NH | H NH, NH, Two molecules of Porphobilinogen 5-aminolevulinate (first precursor pyrrole) Figure 34-5. Biosynthesis of porphobilinogen. ALA synthase occurs in the mitochondria, whereas ALA dehydratase t present in the cytosol. Docsity.com Conversion of porphobilinogen to uroporphyrinogens Usually, type III is formed but in certain porphyrias, the type I isomers are formed in excess. These compounds are not conjugated due to the methylene groups. Oxidation is catalyzed by light leading to formation of the colored porphyrins. Docsity.com Addition of iron to protoporphyrin 4 wo) tom Fe" M | aid | 7} FERROCHELATASE ps Ty P Vv P OM Po oOM Protoporph: Heme yn ol ter (prosthetic group of hemogiodin) (parent porphyrin of heme) Figure 34-4, Addition of iron to protoporphyrin to form heme. Docsity.com Absorption spectrum of hematoporphyrin Porphyrins have a very strong absorbance due to extended conjugation of double bonds. Porphyrins are used in cancer phototherapy. Tumors often take up more porphyrins than normal tissue. Lasers will excite the porphyrin to a high energy intermediate that breaks down and resleases cytotoxic agents that kill the tumor. Accumulation of porphyrinogens can cause sensitivity to light leading to skin damages Docsity.com Intermediates, enzymes, and regulation of heme synthesis Mutations in in enzymes 2- 8 cause the porphyrias. Regulation of heme synthesis occurs at ALA synthase by a repression-derepression mechanism mediated by heme. The dotted lines indicate the negative regulation by repression. Docsity.com