Involved in the biosynthesis of a nickel-pincer cofactor ((SCS)Ni(II) pincer complex). Carboxylates the pyridinium ring of nicotinic acid adenine dinucleotide (NaAD) and cleaves the phosphoanhydride bond to release AMP and generate pyridinium-3,5-biscarboxylic acid mononucleotide (P2CMN) (PubMed:27114550). LarB can hydrolyze NaAD directly or it first forms an adduct with NaAD that releases AMP and reacts with bicarbonate/CO2 to generate P2CMN (PubMed:27114550). Is required for the activation of the lactate racemase LarA (PubMed:24710389). May also be involved in the activation of other nickel-pincer cofactor-dependent enzymes (PubMed:27114550). deamido-NAD(+) + hydrogencarbonate = AMP + 2 H(+) + pyridinium-3,5-dicarboxylate mononucleotide Induced by L-lactate and repressed by D-lactate. Is thus regulated by the L-lactate/D-lactate ratio. Makes part of the lar operon (larABCDE). Deletion of this gene leads to a loss of lactate racemase activity.