Amino Acids Flashcards
Means that amino acids contain both acidic and basic groups
Amphoteric (zwitterion)
Amino acids may have a positive, negative, or neutral charges, depending on the _____
pH
pH>7.4 , when a base is added to the amino acid resulting molecule has a _______ charge
Negative
pH=7.4 , internal transfer of a hydrogen ion from the -COOH group to the -NH2 group results in a _________ charge
Neutral
pH<7.4 decrease in pH by adding an acid results in a _______ charge
Positive
Defined as the pH at which net charge is zero; i.e. There are equal numbers of positive and negative charges
Isoelectric point
If pH > pl
Amino acid has a negative charge
If pH < pl
Amino acid has a positive charge
Proteins act in vivo as a _______ _______ due to their acid-base properties
Mild buffer
Four essential amino acids
Leucine. Isoleucine, Valine, Methionine, Tryptophan, Phenylalanine, Threonine, Lysine
Formed when the alpha amino group of one amino acid is covalently linked with the alpha-carboxyl group of a second amino acid
A peptide bond
The formation of glucose from non-carbohydrate sources, such as amino acids, glycerol, or fatty acids
Gluconeogenesis
Starting and ending products of gluconeogenesis
S: amino acids/glycerol/fatty acids
E: glucose
The process of amino group removal or transfer to make different amino acids
Transamination
Starting and ending products of transamination (2 of them)
S: glutamic acid/Oxaloacetate
E: alanine/aspartate
The removal of the amino group, forming toxic ammonia
Deamination
Starting and ending products of deamination
S: Ammonia
E: Urea
Organ in which the metabolic/catabolic pathways occur in the body
liver
occurs when the plasma levels of the amino acid are normal, but the renal reabsorptive mechanism is defective
Renal Aminoaciduria
______ plasma levels and _______ urine levels of amino acids in renal aminoaciduria
normal; increased
Defect in renal tubular reabsorption of cystine, ornithine, lysine, and arginine; most common error of amino acid transport
cystinuria
Three primary renal aminoacidurias
cystinuria, hartnup disease, and fanconi syndrome
prone to renal calculi made of cystine; cystine crystals on urine microscopic
lab findings in cystinuria
Increased urinary excretion of neutral monocarboxylic amino acids
Hartnup Disease
Patients have a nicotinamide (vit B) deficiency, so they can have pellagra (red, scaly rash), plus neurological and muscular abnormalities
Clinical features of hartnup disease
renal dysfunction of the proximal convoluted tubule
Fanconi Syndrome
polyuria, dehydration, hypokalemia, acidosis, osteomalacia, cannot reabsorb necessary nutrients, bowing of the legs, low weight/height, abdominal distention, enlargement in wrist and ankle joints
clinical features of fanconi syndrome
plasma level of one or more amino acids exceeds the rena threshold
overflow aminoaciduria
______ plasma levels and _______ urine levels of amino acids in overflow aminoaciduria
Increased; Increased
Due to a deficiency or absence of phenylalanine hydroxylase enzyme
Phenylketonuria (PKU)
spastic movements and seizures, sever mental retardation if untreated, eczema, feeding difficulties, vomiting, delayed mental/social development, hypopigmentation, Increased serum phenylalanine, Decreased serum tyrosine, increased urine phenylpyruvic acid
Clinical features of PKU
Due to fumarylacetoacetase deficiency
Type I Tyrosinemia
causes cirrhosis and renal damage leading to fanconi, elevated serum and urine tyrosine levels, elevated methionine in serum
Clinical features of Type I tyrosinemia
Due to tyrosine aminotransferase deficiency
Type II Tyrosinemia
skin lesions, ocular abnormalities (corneal dystrophy), elevated serum and urine levels of tyrosine, tyrosine crystals in urine, serium methionine NOT increased
clinical features of Type II Tyrosinemia
due to 4-hydroxyphenylpyruvate dioxygenase deficiency
Type III Tyrosinemia
mild mental retardation, seizures, periodic loss of balance and coordination, increased serum tyrosine
Type III Tyrosinemia
caused by a defect in the enzyme homogentisic acid oxidase
Alkaptonuria
homogentisic acid inreases in serum and urine, urine turns brown/black when exposed to light and air or when alkali is added, ocular ochronosis
clinical features of Alkaptonuria
most commonly caused by a defect of CBS (cystathionine beta synthase)
homocystinuria
both methionine and homocystine are increased in serum and urine, ocular (lens displacement) and skeletal abnormalities (knock knee), cardiovascular problems (thromboli due to sticky platelets), pigeon chest
clinical features of homocystinuria
due to a defect in the enzyme alpha-ketoacid decarboxylase; also known as branched chain aminoaciduria due to excretion of the branched chain amino acids valine, leucine, and isoleucine
Maple Syrup Urine Disease (MSUD)
symptoms include hypoglycemia, ketoacidosis (blood and urine), lethargy, poor appetite, vomiting, convulsions, detected by the 11th day of life, maple syrup odor, increased ketone bodies
MSUD clinical features
Amino acids can be measured using 3 screening methods
Thin layer chromatography (TLC), photometric screening tests, and Guthrie test
three quantitative testsf for the presence of aminoacidurias
ion exchange chromatography, gas liquid chromatography (GLC), and high performance liquid chromatography (HPLC)
