Metabolic Classification of the Amino Acids PDF
Preview Metabolic Classification of the Amino Acids
Metabolic Classification of the Amino Acids **EEsssseennttiiaall aanndd NNoonn--eesssseennttiiaall * Glucogenic and Ketogenic 1 Essential Amino Acids • Of the 20 amino acids that make up proteins 10 of them can be synthesized by the human body •• TThhee ootthheerr 1100 aammiinnoo aacciiddss mmuusstt bbee aaccqquuiirreedd from food sources. These amino acids are known as essential amino acids 2 Essential Amino Acids Complete protein Incomplete protein • Contains all 10 (cid:1) Lack one of more of the essential amino acids essential amino acids • Proteins derived from (cid:1)(cid:1) MMoosstt vveeggeettaabbllee pprrootteeiinnss aanniimmaall ssoouurrcceess aarree are incomplete proteins complete proteins (cid:1) Beans are an exception to • Beans contain some this generalizations complete protein as well 3 Essential Amino Acids in Humans • Required in diet • Humans incapable of forming requisite ccaarrbboonn sskkeelleettoonn • Arginine* • Lysine • Histidine* • Methionine • Isoleucine • Threonine • Leucine • Phenylalanine • Valine • Tryptophan * Essential in children, not in adults 4 Non-Essential Amino Acids in Humans • Not required in diet αααα • Can be formed from -keto acids by ttrraannssaammiinnaattiioonn aanndd ssuubbsseeqquueenntt rreeaaccttiioonnss • Alanine • Glycine • Asparagine • Proline • Aspartate • Serine • Glutamate * • Cysteine (from Met ) • Glutamine * • Tyrosine (from Phe ) * Essential amino acids 5 Essential and Nonessential Amino Acids Nonessential Essential Alanine Arginine* Asparagine Histidine* Aspartate Isoleucine Cysteine Leucine Glutamate Lysine Glutamine Methionine Glycine Phenylalanine Proline Threonine Serine Tyrptophan Tyrosine Valine Amino acids are classified as glucogenic or ketogenic (cid:2) Glucogenic amino acids are degraded to compounds that can be used as carbon skeletons for glucose synthesis via gluconeogenesis Ketogenic amino acids are degraded to ccoommppoouunnddss tthhaatt ccaann oonnllyy bbee uusseedd ttoo ggeenneerraattee tthhee ketone bodies Both Glucogenic and ketogenic amino acids: Several amino acids are classified as both glucogenic and ketogenic because of their degradation products Glucogenic Amino Acids αααα • Metabolized to -ketoglutarate, pyruvate, oxaloacetate, fumarate, or succinyl CoA Phosphoenolpyruvate Glucose •• AAssppaarrttaattee •• MMeetthhiioonniinnee •• AAllaanniinnee • Asparagine • Valine • Serine • Arginine • Glutamine • Cysteine • Phenylalanine • Glutamate • Glycine • Tyrosine • Proline • Threonine • Isoleucine • Histidine • Tryptophan 8 Ketogenic Amino Acids • Metabolized to acetyl CoA or acetoacetyl CoA AAnniimmaallss ccaannnnoott ccoonnvveerrtt aacceettyyll CCooAA oorr acetoacetyl CoA to pyruvate • Tryptophan • Phenylalanine • Leucine * • Tyrosine • Lysine * •Isoleucine • Threonine * Leucine and lysine are only ketogenic 9 Properties of Amino Acids
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