Developmental patterns and specificities of alkaline phosphatase in the embryonic chick limb☆

[摘要] Alkalinephosphataseispresentintheearlychicklimbbudandinmajorcomponentsoftheolderbud,butthedevelopmentalpatternsoftheenzymearedistinctiveforeachtissue.Theentirebudhashighactivityduringearlyphasesofgrowthbut,ashistologicaldifferentiationbegins,itdecreasessharply.Activityoftheenzymefrommusclefallsuntilday11astherateofcellproliferationsubsides;itshowsaphaseofacceleratedactivity,however,duringdays12–16,whichmaybeassociatedwithchangesintherateofcarbohydrateaccumulation.Intheintegument,activityoftheenzymerisesduringearlystagesoffeathergrowth,butafterday12itdecreasesprecipitouslyduringregressionofthepulp.Bonephosphatase,whichhasthehighestactivity,increasescontinuouslyinactivityduringdevelopment,parallelingtheprogressofcalcification.Limbphosphatasesweretestedforsubstratespecificityonβ-G1-P,G-1-P,G-6-P,6-PG,F-P,PEP,AMP,ATP,NAD,andNADP.Allsubstrateshavingfreephosphategroupsweredephosphorylated,butthephosphodiesterlinkageofNADwasnotattacked.Relativetoactivitywiththereferencesubstrate,β-G1-P,muscleandintegumentaryenzymeshadhighactivitieswithmostglycolyticintermediatesandAMPandATP,whereastheactivityofbonephosphatasewasrelativelymuchlower.Treatmentwithdetergentsorwithseveralproceduresextensivelyusedforextractingphosphatasesofadultmammalsdidnotcausesignificantsolubilizationofphosphatasefromanylimbtissue.However,theenzymesofmuscleandintegumentwereliberatedwithbutanol,andfurtherpurifiedto95-fold.Itwasnotpossibletoachievemuchsolubilizationofbonephosphatase,andthenatureoftheparticletowhichitisboundisunknown.Electrophoreticanalysisindicatesthatheterogeneityexistsnotonlybetweenthephosphatasesofboneandsofttissues,butalsowithineachofthesofttissues.Theboneenzymeischaracterizedbyasinglebandattheoriginandseveralanodicsmears,whereastheidenticalpatternsofmuscleandintegumentaryenzymesshoweightzonesofactivity.Eachzoneiscapableofdephosphorylatingidenticalsubstrates,suggestingthatthemultiplebandsofasingletissuemaybeisozymesofalkalinephosphatase.

[学科分类] 生物科学（综合）