Kmaels introduces the difference between papain and trypsin
Q: Is there any difference between papain and trypsin in digesting tissue blocks? Which one is better?
Answer: The commonly used cell digestion solution is trypsin, whose function is to hydrolyze the protein (such as extracellular matrix) between cells, change the connection between cells, and disperse the tissue or cell sheet into single cells to make cells The suspension was used for further experiments.
Papain (Papain) is a pure natural biological enzyme derived from papaya fruit, referred to as papain; papain is a proteolytic enzyme with a molecular weight of 27000u, which is composed of a single peptide chain and contains 212 amino acid residues . At least three amino acid residues exist in the active center of the enzyme, they are Cys25, His159 and Asp158, and the other six cysteine ​​residues form three pairs of disulfide bonds, and none of them are in the active site. . Papain has a very strong hydrolytic capacity for animal and plant proteins, esters, amides, etc. It is a broad-spectrum enzyme preparation, and its optimal action on ovalbumin and cool protein is pH 7. Papain is a thiol protease that can hydrolyze proteins And the carboxyl terminus of arginine and lysine in polypeptides. And can preferentially hydrolyze those peptide bonds with amino acids with two carboxyl groups or aromatic L-amino acids at the N-terminal of the peptide bonds. It is also possible to degrade chitosan in the plant cell wall by cutting the B- (1,4) glycosidic bond of chitosan. It breaks down more and wider protein substrates than pancreatin.
Slightly soluble in water, glycerin, colorless or light yellow aqueous solution, sometimes milky white; almost insoluble in organic solvents such as ethanol, chloroform and ether. It is most suitable for PH value of 5.7 (generally 3 to 9.5 is acceptable). It also has a role in neutral or acidic state, isoelectric point pI8.75; most suitable for temperature 55 to 60 ℃ (generally 10 to 85 ℃), resistant It has strong thermal property and will not be completely inactivated at 90 ℃. It is susceptible to the inhibition and destruction of heavy metal ions (Fe3 +, Cu2 +, Hg +, Pb +, etc.) and oxidants, and the reducing substances are activated. Cell digestion can also be prepared with 0.1 mol / L phosphate buffer, pH 7.2.
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