小小整理網站 Smallcollation: 胺基酸(amino acid)

同半胱胺酸是甲硫胺酸(Methionine，人體必需胺基酸之一)代謝過程中的一種中間產物，而存於動物體內的胺基酸。研究證實過量的同半胱胺酸在體內堆積，會造成許多組織的損傷。研究證據顯示:血液中含有高量的同半胱胺酸，是導致心臟病的重要危險因子。因為過量的同半胱胺酸會在動脈壁上聚合、堆積，而會使膽固醇沉積，造成動脈硬化產生。生活型態的改變，可能對病情的控制是有幫助的。依照最近的研究顯示，喜好抽菸和喝咖啡的族群，體內的同半胱胺酸濃度有偏高的現象產生。這些發現，與「過量的抽菸和咖啡因攝取，會增加心血管疾病的危險率」的相關研究結果是一致的。

▼胺基酸(amino acid)相關顯示/隱藏(show/hide)

標籤：生物化學(biochemistry), 胺基酸(amino acid)

胺基酸代謝疾病(amino acid metabolism diseases)

0 意見

Disorder	Biochemical derangement	Classical findings^a
Branched-chain amino aciduria (maple syrup urine disease)	Defective branched-chain amino acid breakdown (Fig. 44-1)	Coma, convulsions, vomiting, respiratory failure in neonate
Branched-chain organic acidurias	Failure of organic acid oxidation (Fig. 44-1), isovaleric, methylmalonic, propionic, etc.	Similar to above, may be metabolic acidemia and odd odor; often confused with sepsis of newborn; urine contains excessive amounts of different organic acids, depending on the nature of the defect; partial defects may present in later infancy or childhood
Glutaric acidurias	Type I: Primary defect of glutarate oxidation (Fig. 44-3)	Severe basal ganglia/cerebellar disease with macrocephaly, onset 1 to 2 years
	Type II: Defect of electron transfer flavoprotein (Fig. 44-3)	Fulminant neurological syndrome of the neonate, often with renal/hepatic cysts, usually fatal
Phenylketonuria (PKU)	Usually defect of phenylalanine hydroxylase. In rare cases, defect of biopterin metabolism (Fig. 44-4, reaction 1)	Normal at birth, mental retardation in untreated children, avoidable with early institution of diet therapy, prognosis less favorable in PKU secondary to defect of biopterin metabolism
Nonketotic hyperglycinemia	Defect of glycine-cleavage system (Fig. 44-5)	Intractable seizures in neonate, usually fatal in first few weeks of life
Homocystinuria	Usually a failure of cystathionine synthase (Fig. 44-2, reaction 5), rarely associated with aberrant vitamin B₁₂ metabolism (Fig. 44-2)	Thromboembolic diathesis, marfanoid habitus, ectopia lentis; mental retardation is frequent
Urea cycle defects	Failure to convert ammonia to urea via urea cycle (Fig. 44-6)	Coma, convulsions, vomiting, respiratory failure in neonate; often mistaken for sepsis of the newborn; mental retardation, failure to thrive, lethargy, ataxia and coma in the older child; associated with hyperammonemia and abnormalities of blood aminogram
Defects of biotin metabolism	Failure to “activate” biotin, which is important in carboxylation of organic acids	Hypotonia, ataxia, acidosis, coma, dermatitis in the neonate; mental retardation and deafness in the older child
Disorders of glutathione metabolism	Defective synthesis of glutathione, the major intracellular antioxidant (Fig. 44-7)	Spinocerebellar degeneration, mental retardation, cataracts, hemolysis; severe acidosis in some cases
Disorders of GABAmetabolism	Often an absence of succinic semialdehyde dehydrogenase	Hypotonia, ataxia, mental retardation in the older child; increased urine 4-OH-butyric acid
Canavan's disease	Absence of N-acetylaspartate acylase	Rapidly progressive demyelinating disease of infancy

資料來源：For disorders of carbohydrate metabolism and the primary lactic acidoses, see Chap. 42.

標籤：生物化學(biochemistry), 疾病(disease), 胺基酸(amino acid)

麩胺酸衍生物(Glutamate derivatives)

0 意見

A. Glutamate的衍生物γ-aminobutyric acid (GABA)，為中樞神經系統之抑制性神經傳導物

B.代謝：

I. L-Glutamate脫羧形成GABA

II.脫羧過程中有Vit.B₆的參與

▼胺基酸(amino acid)相關顯示/隱藏(show/hide)

▼胺基酸應用(amino acid application) 顯示/隱藏(show/hide)

標籤：生物化學(biochemistry), 神經傳導(Nerve conduction), 胺基酸(amino acid)

色胺酸衍生物(Tryptophan derivatives)

0 意見

A.Tryptophan是Serotonin(血清素)、Melatonin(退黑激素)、Niacin(菸鹼酸)的前驅物

B.Niacin（菸鹼酸）和NADH及NADPH的生成相關；而Serotonin(血清素)和憂鬱症相關

資料來源：維基百科
C.血清素(Serotonin)
I.大腦所產生之神經傳導物質，可使人有興奮的感覺
II.缺乏或功能不佳時造成心情不佳，可能導致憂鬱症及自殺等問題
III.在細胞間分泌不足或受體不足時都會造成憂鬱的感覺
IV.當情緒低落時，血清素回收運輸體會受到刺激而增加，吃掉更多分泌出來的血清素，而導致憂鬱
V. 憂鬱症或心情不好時可補充雞肉、牛肉、堅果類、香蕉…等食品，或是直接服用含serotonin的藥物。
D. 褪黑激素(Melatonin)
I.腦部松果體所分泌的激素，松果體的體積很小
II.其分泌受兩種因素影響：
i.光暗
ii.晝夜韻律
III. 愈年輕的人Melatonin分泌越多，老年人因為松果體退化而分泌量降低，睡眠時間因此縮短