Catalysis by a New Sialidase, Deaminoneuraminic Acid Residue-Cleaving Enzyme (KDNase Sm), Initially Forms a Less Stable α-Anomer of 3-Deoxy-D-Glycero-D-Galacto-Nonulosonic Acid and Is Strongly Inhibited by the Transition State Analogue, 2-Deoxy-2,3-didehydro-D-glycero-D-galacto-2-nonulopyranosonic Acid, But Not by 2-Deoxy-2,3-didehydro-N-acetylneuraminic Acid