Bio Question

[TawMus]

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I read somewhere that basic amino acids are positively charged and hydrophillic. I'm having a little trouble grasping the concept. Someone help me plz.

 

[niranjan162]

its depends on the amino acid side group and the pH the amino acid is. Whether its hydrophobic or not also depends on the side group

 

[unsung]

I read somewhere that basic amino acids are positively charged and hydrophillic. I'm having a little trouble grasping the concept. Someone help me plz.

Basic amino acids are basically good bases 😉 Meaning they *want* to grab protons. So the generic structure of an amino acid is R-NH2-C(O)-COOH. Kind of hard to draw on here, but for a basic amino acid (i.e. histidine, lysine, or arginine), that R group will have a basic atom in it, which will get protonated. Take lysine, the N on its R group will grab a proton and become -NH3, meaning the N now carries a positive charge.

I don't know how clear that explanation was. Basically, and this confused me at first too, basic amino acids are positive because after the nitrogen grabs a proton it's positive. So don't get confused with thinking base = anion... think instead about what bases like to do (grab protons) and what would result from that. Conversely, acidic amino acids like to be negative because they like to lose their acidic protons.

 

[TawMus]

That makes sense. Thanks man.