I was &pry to get your letter apcc espau$ldly the information that you my
iaate isolated uridixm frkphosphate froat nslscle.  f remember very well the
data whioh Euby showed me when 'I vas in Wadisen, brit, as pou poht out,  that
iarpreshlfon at that tiate was that you atight be dealing with adenosine Detm-
pfiosphatca.
dim, this amst bmre Wen a mixbe containing; some adenosine plyphosphate
BJ well.

In view of the lower absorption croef'ficfent of uridine and cyti-

'phs history of owr interest ln u%LIp goes Xke tMsr
apt, f wondered whether UTg n&&t be a condensing agest lib dTP follllaiag a
ppophosphate brlue wit& g~uaose-l-phespb&e.  Reuently Ted Park (at Oanp
DetrfGk) was and enuugh to sand me some ur%dins diphosphate %solated froa
his Stmh. aureu$ rrcmpotmd.
pyruvate am3 a raf;her pxr%fled transferflag enzpe fmni rabbit muscle,  tbre
was a quantitative eonversion to uridine triphosphate.
work w%th u9ep aod glucose-1-phosphate 3n yea& axtracts, but the wsnlte are
too ancer%ain to be relied upon.
adequate amom~s of uridfna diphosphate for further work.
poor laek with ysast &E a BIYUZ"ICB aratesial, the yields being far lower tban
antlaipated from LeloirBa report,
froat gtaah. aweus amcwdlag to Park and Johnsan*s mefihbd.

When Leloirgs work cam

We observed tbt in a sys%em contsinlng phospho-

We did some preliminary

AB the momn% our chief concern &a to get
              We have had very

We are just about to try to prepare it

Sime the ensJnaatOa rynthesls of VTP was eamied m$ in a rather prified
system and we ham not had the problem of separatfw it fram adenine COIR-
pounds, f probably wmmt be of mah help on year separation pmblent.
might suggest this, howwar: fn wme other work we were doizrg rcwentlp, we
a*tdnard very handsome ehromategrsms of &TP an Dousx-1 chloride udng .01
3Cl in .Os & BsCl as the eluting agent.  Aha, it is asg. inrpression that the
etbi1if;y of mercu~50 salts to precipitate ATP in acrid solution is related $0
the amino grauy, and this

I

prove fo be a means of separation.

Arthur Earnberg