02 PROTEINS: aminoacidopathies + protein structure Flashcards
Class of inherited errors of metabolism in which there is an enzyme defect that inhibits the body’s ability to metabolize certain amino acids
Aminoacidopathies
Deficient enzyme in phenylketonuria
Phenylalanine hydroxylase
The first newborn test is for ___
PKU
In the newborn, the upper limit of normal for phenylalanine concentration in the blood is ___
120 umol/L
PKU is due to mutation in the ___ gene
PAH
Mild PKU phe level
600-1200 umol/L
non-PKU phe level
180-600 umol/L
Urine odor for PKU px.
Mousy/musty odor
Women with untreated PKU during pregnancy almost always have infants who are ___ and ___ ___
microcephalic
mentally retarded
A screening test for PKU that is based on bacterial inhibition
Guthrie test
The Guthrie test for PKU is sensitive enough to detect serum phenylalanine concentrations of ___ umol/L
180 umol/L
The growth inhibitor for Guthrie test for PKU
B-2-thienylalanine
Bacteria used as a control in the Guthrie test
Bacillus subtilis
A quantitative direct measurement of phenylalanine
Microfluorometric assay
A method of phenylalanine determination that is more adaptable to automation and is not affected by the presence of antibiotics
Microfluorometric assay
In the Microfluorometric assay for PKU determination, the wavelengths required are ?
360 and 530 nm
Gold standard for PKU screening
MS/MS
Treatment for PKU
Sapropterin dihydrochloride (Kuvan)
MOA of sapropterin dihydrochloride
Enhances phenylalanine hydroxylase
An aminoacidopathy that s caused by deficiencies of different enzymes in the metabolic pathway of tyrosine
Tyrosinemia
The mutated gene in tyrosinemia type 1
FAH (fumaril-acetoacetate hydrolase) gene
An amoniacidopathy that leads to liver cancer, kidney failure, and peripheral neuropathy
Tyrosinemia type 1
Tyrosinemia type 1 causes ___-like odor
cabbage
The mutated gene in tyrosinemia type 2
TAT (tyrosine-aminotransferase) gene
An aminoacidopathy that manifests as impaired mental development, photophobia, eye pain and redness, and painful skin lesions on the palms and soles of the feet
Tyrosinemia type 2
Last of the 5 enzymes important for tyrosine metabolism
FAH
First of the 5 enzymes important for tyrosine metabolism
TAT
Second of the 5 enzymes important for tyrosine metabolism
HPD
Mutated gene in type 3 tyrosinemia
HPD (4-hydroxyphenylpyruvate dehydrogenase)
An aminoacidopathy that manifests as impaired mental development, seizures, and some intermittent loss of balance and coordination
Tyrosinemia type 3
An aminoacidopathy that manifests as a neurological condition
Tyrosinemia type 3
Diagnostic criteria for tyrosinemia
elevated tyrosine conc. using MS/MS
elevated succinylacetone conc.
Treatment for tyrosinemia
low-protein diet
NTBC
MOA of NTBC
Inhibits production of succinyl acetone
This treatment prevents the formation of maleyacetoacetic acid which converts to succinylacetoacetone
NTBC
Mutated gene in alkaptonuria
HGD (homogentisate oxidase)
An aminoacidopathy that causes metabolic deficiency in tyrosine and phenylalanine
Alkaptonuria
T/F: In alkaptonuria, the symptoms are typically not present until their third decade of life
T
Ochronosis is presented in which aminoacidopathy?
Alkaptonuria
A manifestation of dark blue-black pigmentation in the urine in alkaptonuria
Ochronosis
T/F: alkaptonuria can result to arthritis-like degeneration if accumulated in the cartilage
T
The screening test for alkaptonuria consists of a test tube with what reagent?
FeCl
The positive result for FeCl test
Black coloration
Management of alkaptonuria
Increased vitamin C dosage
MOA of increased vitC dosage
slows down accumulation of homogentisate
An aminoacidopathy that presents lethargy, vomiting, lack of appetite, failure to thrive within a week
Maple syrup disease
The defect in maple syrup disease is the absence of ___
branched-chain a-ketoacid decarboxylase (BCKD)
Maple syrup disease occurs one in ___ births
185 000
Inheritance pattern of maple syrup disease
autosomal recessive
The growth inhibitor for the modified guthrie test for maple syrup disease
4-azaleucine
The excitation and fluorescence wavelength required for the microfluorometric assay for maple syrup disease
360 nm - excitation
450 nm - fluorescence
Inheritance pattern of isovaleric acidemia (IVD)
autosomal recessive
An aminoacidopathy that causes a distinctive odor of sweaty feet
Isovaleric acidemia
Treatment for isovaleric acidemia
protein-restrictive diet
oral administration of glycine and carnitine
Inheritance pattern of homocystinuria
autosomal recessive
The lacking enzyme in homocystinuria
systathione B-synthetase
The inhibitor used for the modified guthrie test for homocystinuria
L-methionine sulfoximine
Treatment for homocystinuria
dietary restriction of proteins
high doses of vitB6
The amino acid affected in homocystinuria
methionine
An aminoacidopathy found in the Japanese population
Citrullinemia type 2
A urea cycle disorder that takes place in the liver cells to process excess nitrogen
Citrullinemia
The mutated gene in citrullinemia type 1
ASS1 gene
The mutated gene in citrullinemia type 2
SLC25A13
Treatment of citrullinemia
Arginine supplementation
Administration of sodium benzoate and sodium phenylacetate
A urea cycle disorder that increases ammonia and damages the liver, nervous system, and causes toxicity to blood
Arginosuccinic aciduria (ASA)
T/F: NBS can differentiate all aminoacidopathies
F (in the case of citrullinemia and ASA, NBS cannot)
Treatment for ASA
Arginine supplementation
Administration of sodium benzoate and sodium phenylacetate
Mutated gene in cystinuria
SLC3A1 and SLC7A9
An aminoacidopathy characterized by inadequate reabsorption of cystine during urine formation in the kidneys
Cystinuria
An aminoacidopathy associated with Fanconi’s syndrom
Cystinuria
Treatment for cystinuria
Increased fluid intake (4L per day)
Penicillamine
Percutaneous nephrolithotripsy
Screening tests for cystinuria
Urine test using cyanide nitroprusside
Ion exchange chromatography
Positive result for urine test
Red-purple coloration
Enzyme defect in albinisim
tyrosinase
Fasting requirement for screening of aminoacidopathy
6-8 hours
The urine sample required for screening of aminoacidopathy
first morning specimen
Protein structure:
refers to the number, type, and sequence of amino acids
primary
Protein structure:
commonly formed arrangements stabilized by hydrogen bonds between nearby amino acids within the protein molecule
secondary
Protein structure:
can either by a-helix or b-pleated
secondary
Protein structure:
represents the strength and flexibility of the protein
secondary
Protein structure:
overall shape and conformation
tertiary
Protein structure:
structure that results from the interaction of more than one protein molecule
quaternary