public static final boolean isCharged(char aa) {
		if (negChargedAAs.contains(String.valueOf(aa))) {
			return true;
		}
		else if (posChargedAAs.contains(String.valueOf(aa))) {
			return true;
		}
		return false;
	}
public static final boolean isCharged ( char aa ) { if ( negChargedAAs . contains ( String . valueOf ( aa ) ) ) { return true ; } else if ( posChargedAAs . contains ( String . valueOf ( aa ) ) ) { return true ; } return false ; }
At pH=7, two are negative charged: aspartic acid (Asp, D) and glutamic acid (Glu, E) (acidic side chains),
and three are positive charged: lysine (Lys, K), arginine (Arg, R) and histidine (His, H) (basic side chains).

@param aa The one-letter amino acid code
@return true if amino acid is charged