text: Yo, check it out, let me break it down for you,
  Human factor XII, activated, it's true.
  Limited proteolysis with trypsin's the plan,
  Isolate beta-factor XIIa, make it stand.
  
  DEAE-Sephacel column chromatography,
  Is the method to separate, scientifically.
  Complete amino acid sequence, gotta know,
  Peptides digested, three enzymes in a row.
  
  Trypsin, chymotrypsin, Staphylococcus aureus V8,
  Breaking it down, revealing what's great.
  Methionyl and tryptophyl bonds, chemically cleaved,
  Unveiling the secrets, gotta believe.
  
  beta-Factor XIIa, a glycoprotein, yo,
  Heavy chain and a light chain, ready to flow.
  Disulfide bond holds 'em tight, no doubt,
  Amino acids linked, that's what it's about.
  
  Carbohydrate attached, asparagine's the site,
  Residue 61 in the heavy chain, just right.
  The heavy chain's sequence, homology's seen,
  Similar to other serine proteases, it's keen.
  
  Plasmin, thrombin, factor IXa, and factor Xa,
  Pancreatic enzymes, yo, that's the spa.
  Factor XII, the precursor, laying the foundation,
  Serine protease, part of the coagulation sensation.
  
  That's the knowledge drop, the science rap,
  Factor XII's story, no need to clap.
  Coagulation cascade, it's all in the mix,
  Now you know the facts, let it stick.