Sunday, May 9, 2010

Times when biology knowledge comes in useful

I love pineapple. Really, really love pineapple. Unfortunately, it irritates my mouth. I recently found out that this is not only due to the acidity -- pineapple contains a protease, bromelain. Bromelain will eat your face pretty effectively -- in fact, apparently there's a lot of interest in using it for wound debridement. [visceral shudder]

Unfortunately, the last time I ate a ton of pineapple all at once, I forgot about the protease until it was too late. But then I thought, "aha! I can saturate the protease with another type of protein and my mouth will remain unaffected!" Then I drank some milk.

Bio labs use milk as a generic solution of "loads and loads of proteins" in a lot of techniques. The one that springs to mind is Western blots. Basically, you run proteins through a gel that separates them by size and/or charge, to help identify what proteins you've got in the sample. Then you put your gel onto a nitrocellulose membrane that adsorbs proteins, so the spots from the gel transfer onto the membrane. Next, you want to probe the membrane with antibodies that should bind to your protein of interest, if it's on the membrane, and light up. But what's the problem? Antibodies are proteins, and the nitrocellulose membrane grabs onto all the proteins it touches, so unless you do something the antibody will just bind to the entire blot. What to do? Enter the milk! If you soak the membrane in milk before adding antibodies, then the milk proteins will bind all over the place and saturate the membrane, so then you can add antibodies without fear.

I told Zek about this and she mentioned another method for taking the bite out of pineapple: soak it in salt water. Apparently this is traditional in some places. We speculated that the high salt denatures the bromelain. I have yet to test whether this works or not, and whether it affects the taste.

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