Mutational Analysis of Bacterial NAD + -dependent DNA Ligase: Role of Motif IV in Ligation

A latching system such as for matable first and second electrical connectors having matable pin and socket contact terminals comprises a pair of opposing latching arms each extending forwardly from a joint on opposing sides of the second electrical connector in cantilever fashion, to latchingly engage behind a pair of corresponding latching projections on opposing sides of the first electrical connector when the connectors are fully mated. The latching projections are high and abrupt and relatively sharp having steep forward and rearward surfaces generating substantial resistance to latching during mating. When the latching sections of the latching arms reach the sharp outer tips of the latching projections, the resistance to latching suddenly ceases and the latching sections immediately latch behind the respective projections without hanging up on top thereof, assuring full mating and providing a snap action which provides an audible signal. The latching system also provides resistance to delatching during unmating of a similar substantial level to the resistance to latching.