▁mechanism ▁in ▁the ▁presence ▁of ▁M n 2 + . ▁The ▁reason ▁why ▁this ▁tr in uc le ot ide ▁rather ▁than ▁the ▁complement ary ▁t et ram er ▁catal y ze ▁this ▁reaction ▁may ▁be ▁because ▁the ▁U U U - AA A ▁pair ing ▁is ▁the ▁weak est ▁and ▁most ▁flexible ▁tr in uc le ot ides ▁among ▁the ▁ 6 4 ▁conform ations , ▁which ▁provides ▁the ▁binding ▁site ▁for ▁M n 2 + . ▁ ▁Ph osph ory l ▁transfer ▁can ▁also ▁be ▁catal yz ed ▁without ▁metal ▁ ions . ▁For ▁example , ▁pan cre atic ▁rib on uc lease ▁A ▁and ▁he pat itis ▁delta ▁virus ( HD V ) ▁rib oz ym es ▁can ▁catal y ze ▁the ▁cle av age ▁of ▁R NA ▁back bone ▁through ▁acid - base ▁catal ysis ▁without ▁metal ▁ ions . ▁ ▁H air pin ▁rib oz yme ▁can ▁also ▁catal y ze ▁the ▁self - cle av age ▁of ▁R NA ▁without ▁metal ▁ ions ▁but ▁the ▁mechanism ▁is ▁still ▁unclear . ▁ ▁Rib oz yme ▁can ▁also ▁catal y ze ▁the ▁formation ▁of ▁pe pt ide ▁bond ▁between ▁adjacent ▁am ino ▁acid ▁by ▁lower ing ▁the ▁activation ▁entropy . ▁ ▁Activ ities ▁ ▁Although ▁rib oz ym es ▁are ▁quite ▁rare ▁in ▁most ▁cells , ▁their ▁roles ▁are ▁sometimes ▁essential ▁to ▁life . ▁ ▁For ▁example , ▁the ▁functional ▁part ▁of ▁the ▁rib os ome , ▁the ▁bi ological ▁machine ▁that ▁transl ates ▁R NA ▁into ▁prote ins