What is the structural and functional analysis of catalase?

If this is an A level biology Q, then hellfire (God help us!! - all hell breaking lose?? ) has hit the nail on the head - at A level, you need to work out [v quickly in an actual exam] what aspect of the syllabus the Q is intended to test.

Its a biochemistry question, what is the structural and functional analysis of catalase?

Catalase is an enzyme which is a polymer of amino acids joined by peptide bonds in condensation reactions. The polypeptide chain produced is folded in a-helices and B-pleat sheets. The further folding of the polypeptide chain causes the tertiary structure to arise: hydrogen bonds, ionic bonds and disulfide bridges, which support the shape of catalase’s active site.

If this is an A level biology Q, then hellfire (God help us!! - all hell breaking lose?? ) has hit the nail on the head - at A level, you need to work out [v quickly in an actual exam] what aspect of the syllabus the Q is intended to test.

Here, the use of the specific enzyme catalase has no basis - the Q is testing your knowledge of general enzyme structure and function.

If, on the other hand, you are doing a biochem degree OR studying biochemistry as a med student, then you will need to mention the specificities of the particular enzyme catalase, which to be honest, you would need to google, except to say that the name catalase is an old-fashioned name set before the proper classification and naming of enzymes, and its proper name should be hydrogen peroxide dismutase because its action is as follows:

2H2O2 ------> 2H2O + O2

This reaction is important in human biochemical physiology since it helps eradicate one of the reactive oxygen species, namely H2O2 - i.e. it is one type of anti-oxidant, in common with e.g. Vitamin E [tocopherol] and Vitamin C [ascorbic acid].

M [former medical student]

Wow thank you so much, this is deeply explained. I'm actually a 1st-year biomedical sciences student. Also would you be happy to tell me about any laboratory techniques which are used to analyse the structural and functional analysis of catalase please?

@TheKitty.x

Hi again Kitty (! - believe it or not, there is actually such a name for a girl - I knew one),
Firstly, thank you for your kind words!

Ok regarding your Q, I have not formally read about or learnt any process to e.g. work out the structure of catalase specifically - however, that is not a reason for us to despair!
I am sure we can engineer some kind of answer for that Q by using a little logic:-

Biomedical science is one degree I have not got round to doing, so I am not fully familiar with the content, exam style etc, but could they be testing your knowledge of:
a) general enzyme kinetics? You could draw the graphs of substrate conc-n vs speed of reaction, and enzyme activity against time. If so, you might want to look up how to work out Km using the Lineweaver-Burk double reciprocal plot of 1/v(0) (y axis) against 1/S (x axis)[S is substrate conc-n], in which the intercept on the y axis gives the value of 1/V(max) and the intercept on the x axis gives -1/Km (Km being the substrate conc-n at which the reaction runs at half max velocity).

You would probably need to use radioactively labelled hydrogen (deuterium, H3?) OR some kind of dye in conjunction with a spectrophotometer to assay the reactant (H2O2) or one of the products to measure reaction rate. Radioactivity can then be measured with a liquid scintillation counter OR by autoradiography.

b) technique of working out the amino acid sequence of a protein?:
- (i) Find the no. of polypeptide chains in the catalase by working out the no. of N-terminal ends using dansyl chloride (the full name is a big mouthful); the dansylated polypeptide, when reacted with acid, releases the N-terminal a.a. - the no. of different ones tell us how many polypeptide chains are present.
- (ii) Cleavage of disulphide bridges using a mercaptan (a compound with an -SH group)
- (iii) cleave the polypeptides using proteases [first with endopeptidases to emulate the Tetragammaton's ingenious strategy of protein digestion in the human alimentary tract i.e. if you first break a long chain in the middle to give many small chains, then you have more ends for the exopeptidases to work on - if you believe in him - sorry, I am a proponent of Darwin's theory] to break down each polypeptide and then identify the a.a. sequence. e.g. trypsin which specifically cleaves peptide bonds next to arginine or lysine, etc. I believe chymotrypsin breaks peptide bonds next to aromatic amino acids, but my eidetic memory could be failing (it is 10 yrs since I was a med student).
- (iv) identify detailed a.a. sequence.
- (v) find out the location of disulphide bonds by locating the cystine residues.

Sorry KItty, my lecturers/consultants dubbed me "detail friek"! - I hope you are not falling asleep by now!

I hope I am not leading you up the garden path!

Regards,
M