The way they used to do it was you purify as much of the protein as you can and then test it with a number of chemical reactions. Their reaction would break off the last amino acid in the chain and then scientists would use the machine to determine which of the 20 amino acids it was. Today they predict the amino acid sequence by sequencing the DNA that encodes the protein.
(http://www.newton.dep.anl.gov/askasci/mole00/mole00255.htm)

Studies of the evolutionary relationships at a molecular level have focused on proteins and nucleic acids, protein work was used first because technology to separate proteins was found earlier and it could be applied to the studies. Separation technologies applicable to the studies of nucleic acids, especially once coning methods rendered gene isolations and sequencing a fairly routine matter, within limits.
(Http://www.newton.dep.anl.gov/askasci/mole00/mole00385.htm)

Should people be allowed to access a person's genetic  data?  In my opinion I don't  think that people should be able to access a persons genetic data because even though it might help employers to employ a better much healthier staff, people with genetic disorders might be discriminated against because of any disorders they have.  Schools and colleges might also reject with a genetic disorder or disease because they don't want to deal with it. My point is that of people are able access your or anyones genetic data than they might be some discrimination.