Acid-free paper Acid-free paper Acid-free paper is paper that if infused in water yields a neutral or basic pH (7 or slightly greater). It can be made from any cellulose fiber as long as the active acid pulp is eliminated during processing. It is also lignin- and sulfur-free. Acid-free paper addresses the problem of preserving documents and artwork for long periods. Paper made from wood-based pulp that has not had its lignin removed turns yellow, becomes brittle, and deteriorates over time. When exposed to light and/or heat, the molecules in the acidic paper will break down even faster. Acidic wood-pulp paper became
6TMS neutral amino acid transporter family 6TMS neutral amino acid transporter family The 6TMS Neutral Amino Acid Transporter (NAAT) Family (TC# 2.A.95) is a family of transporters belonging to the Lysine Exporter (LysE) Superfamily. Homologues are found in numerous Gram-negative and Gram-positive bacteria including many human pathogens. Several archaea also encode MarC (see below) homologues. Some of these organisms have 2 or more paralogues. Most of these proteins are of about the same size (180-230 aas) although a few are larger. They exhibit 6 (or in some cases, possibly 5) putative TMSs. A representative list of members belonging to the NAAT family can be found in