practical 1

Question 1

what are two time consuming and costly ways of measuring protein cocentration

Answer 1

amino acid analysis by chromatography

total nitrogen kjedahl method

Question 2

how does the bradford method work

Answer 2

amino acids containing NH3+ groups - lysine and arginine cause coomassie blue ddyes A to go from 465 to 595. so proteins can be quanitified by mixing them with coomassie blue dye and measuring A595

Question 3

what is the sensitivity of the bradford method

Answer 3

1microgram of protein in 5mL assay

Question 4

what is the reliability of the bradford method

Answer 4

not reliable as amount of lysine and arginine in proteins vary

Question 5

is bradford method destructive

Answer 5

yes

Question 6

what is the biuret method

Answer 6

Cu2+ from dilute alkaline copper sulphate binds to peptides with 2 or more peptide bonds 1 Cu2+ binds to 4 NH

Question 7

what is the sensitivity of the biuret method?

Answer 7

insensitive requires 1mg pf protein in assay `

Question 8

is biuret method destructive

Answer 8

yes

Question 9

what is the ultra violet method

Answer 9

aromatic amino accids tryptophan and tyrosine absorb at 280

can use beer lambert to calculate conc

Question 10

what is the sensitivity of the a280 uv method

Answer 10

10 micro grams in 1ml

Question 11

what is the reliability of the a280 uv method

Answer 11

not reliable
amino acid composition assumptions
subject to interferance by nucleic acids