Yes, ARGININE is a Scrabble word!

Letter values in Scrabble US: A 1, R 1, G 2, I 1, N 1, I 1, N 1, E 1.

Is it a valid word?

ARGININE is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

a bitter tasting amino acid found in proteins and necessary for nutrition; its absence from the diet leads to a reduced production of spermatozoa