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A COI"i?AI?ATIV:G S'l'UDY OF TH:S CJ�.S£IN I·liCELL:SS OF CAI-'RINE, OVI NE iU'ID BOVIN:E I1ILKS
A thes i s pr8sented in partial fulfilment of the requirements for the degree of Doc tor of }'hi losophy in rhys iology a-t
I'Ias s ey University.
Barry Charles Hichards6n Novemb er , '1974
ll
Several oifferent hypotheses of casein micelle s
t
ructurehav8 been proposeQ from the data obt2ined in
the
investi�utions carried out on micelles over the past twenty years. Thepresent comparative s
t
udy
ofc�princ (�oat)
and ovine (sheep) casein micelle sy:::otems v1ith that of the bovine 1:.'as made i?:l an attempt to demonstrate the validi t�r of t;hos c ll;ypothcs cs.The casein contents, minero.l levels, o_nd Ca:phosphate ratios in the skim milks �aried between species, but no
significant differences in the Ca:phosphate r�tios in the
casein micelles or the sera were found. There were major dif-
ferences betv;een the electrophoretic p2tterns of the casein saoples from the different snecies. Both caprine and ovine caseins cont�ined two prominent bands in the �-casein region, v1hile ca-orine casein nlso contained ;:1 snmller proportion of its casein in more mobile components (ao-caseins) than the bovine.
�)
Three major
�
-caseinsw
ere observed in ovine casein, and one major a -casein in the mo_jorit;y of the caprine casein samy;les.s
Bovine, caprine a_nd ovine cuseins, isol ated from the whole milks, were separated in
t
ot
heir major components by ion exchane;e chromatography. The K-, (J-, c-J.nd a -cas einss
which were isolated accounted for 15;j, 35;� and 50)j , respect- ively of bovine casein, 10;;, 60'); and 2:;%, respectively of capri:te casein and 10�), Lt-5% and 35�;,s, respec
t
ively
of ovinecasein. The caprine and ovine cascins were identified as
�-,
�- and K-type caseins by their chemical and physical characteristics.11he bovine, caprine and o
v
ine K-cas eins v:ere readily hydrolysed by rennin and were able to stabilize the Ca sensitive as- or ,8-cas eins. Caprine 131- and �2-cas eins which •.-:ere present in equimolar amounts, had nearly identical amino acid compositions, and Here similar to the.t of bovine t3-casein A2•
The ,e1 component, however, contained an additional phosphate residue.
11he temperatm'e dependent Ca sensitivities and the temperature dependent polymerization of the cuprine �-caseins were similar to that of bovine t3-cas ein. Hov1ever,
�
-caseinJ..lJ..
app ear e d to as s ociat e more easily than ��-casein , des pi t e
c
i t s higher net negative charge . Visc os ity measurement s indica t e d that the conformation of the two caprine �-caseins was s imilar t o that of b ovJ..ne �-cas ein , b o th at 4°C and at 25°C .
The maj or caprine a s -cas ein was more s imi lar t o the minor b ovine as3-cas e in than to bovine as 1 -cas ein. This
was demons trat ed by their b eb.avi our on gel e l ectrophore s i s with Mg b uffers , C a s ens i tiviti es , amino aci d compos i t i ons a�d m o lecular wei ght s .
The two ovine �-cas eins were s imilar t o each other , and t o th e caprine and b ovine �-cas eins . The relationship b etween the ovine �-cas eins was s imi lar to that of the
caprine �-cas eins . Two of the thrE.e maj or ovine a -cas eins s were i s o l at e d . Thes e were both s imilar t o e ach o ther , and t o b ovine as1 -cas ein .
The proper t i e s o f t h e a s -cas eins from the thr e e s peci e s were mor e vari ab l e than tho s e of the f1-cas eins, which in turn were more variab l e than the K-cas e ins .
The cas ein mice l l es from caprine , ovine and bovine
milks wer e all highly s o lvat ed and roughly s pherical . Alth ouc;h their s i z e distribut i ons varied , the micel l es were in each
cas e comp o s ed of sub-unit s ab out 1 2 nm in diamet er . G e l chroma tography o f s ub -mice l l ar cas e in aggregat e s from the thr e e s peci es indicat ed that they had s imi lar hydrodynamic s i z es and appear e d to b e in equi l ibrium Hith th eir component cas eins .
The finding that s imilar s ized sub-unit s ar e ·formed in the cas e in micel l es in the milks of the various s p eci es ,
s ugges t s that the di ffering proport i ons of the vari ous
component cas eins must comp ens at e for the differ ences obs erv e d in t h e proper t i e s o f t h e cas eins . I t appeal'S l ikely that n o t enough emphas i s has b e en given t o the rol e of �-cas ein in
micel l e s truct ur e , and �- and as -cas eins may b e int er
changeab l e .
I am grateful to the'fol lowing:
Professor H. E. I'1unford, for supervision and for the collection of samples of sheep milk.
iv
Dr L.K. Creamer, ·N.l. Dairy Research Institute, for guidance and continuing interest, and for obtainin� the
el ectron rnicror;raphs used in this thesis
(
F.'igs .4.2 and 4.3 ) .Dr K.N. Fearce,
N.Z.
Dairy Research Institute, for measuring the cation concentrations and activities in the milks.Analytical Chemistry IJaboratory, N. 6. Dairy Hesearch Institute, for Kjeldahl nitrogen determinations.
I"Ir B. Le ask, 'l'e Arakura, for supplying the goat milk.
Mrs A. Halligan, N.Z. Dairy Research Institute, for assistance with the diagrams.
Mr C.K. Drew, r-lrs P.A. Leyland, l'iiss G . F . Evans and Mr A.R. Matheson, N.3. Dairy Research Institute, for their technical assistance at different p€�iods throughout the course of the work.
I'Ty wife, Joy, for her considerabl e assistance during the preparation of this thesis.
N.Z. Dairy Research Institute, for employment and the use of the facilities during the course of the work.
.
'l'ABL.t.; 01•' C G.l�'l'LJ:LrS
CHAPl'ER
1 G:c.'NE.HAL INTHOlJUCTION1 . 1 1 . 2 1 . 3
C omposi t i on o f Mi lk The CG.seins
Aim of the I nvest i gation
PAHT I A COI"'lf'A:RISON ·o:l!' CAPHI NE, OVI NE AND BOVINE
MI LKS Al�D 'rJ:fEIH CASEIN MICELLES
CHAPTER 3
2.1
2.2 2 . 3
C omposi t i on of Milk
Size Dis tribution of Casein Mic ell es Mo l ecular Wei�1t of C as ein Mic elles
2.4
Vo luminos i ty and Solvat i on o f Cas ein Mic e l l e s2.5 Temperat ur e Dep endent Dis s oc i at ion of Cas e in Mic e l l es
EXFCRIMENT
... �L3.3
Pr eparat ion of Skim l'1ilks Ni trogen Dis tribution
InorGanic Pho sphat e Det erminat i on 3.4 Det erminat i on of C at i on C onc entra
t i ons 3-5
3 . 6 3-7 3 . 8 3 . 9
C at i on Ac t ivity
C itric Ac id C ont ent s El ec trophores is
Fr e e z e- etch El ec tron MicroGraphs
\mo l e Mic e l l e El ec tron Mic ro graphs 3 . 1 0 So lvation o f Cas ein Mic e l l e s :
Ultrac entri fugat i on
3 . 1 1 Solvat i on o f C as ein Mic e l l es :
Page No . 1
1 1 4
7 8
8 9 1 1 1 1
1 2 1 4
1 4 1 4 1 5
1 5 1 5 1 6 1 6 1 6 1 6
1 7
Vi s c os ity Measur ements 1 8
3 . 1 2 Temperatur e Dep endent Di s s oc i at i on of C as e in Mic ell es
3 . 1 3 Gel Chromatography of C�s ein Mic e l l e s at 6°C and 37°C
20
Table of Cont2nts
(
Contd.)CHAPTER 4 CONPOBJI:PION OF C/JRINE, OVIN� AND BOVIN:t; I'1ILKS
4 . 1 Nitrogen, Inorganic Phosphorus and
Citric Acid Contents
4 . 2 Cation Concentrations and Activities
Electrophoresis of the Caseins
Page No.
23
23 25 28 A COI'1PARISON OI•' THB PHOl-l�HTIES 01? THE CASEIN I''IICELLES 28
CHAPI'ER 5
4 . 4
4 . 6
4 . 7 4 . 8
Electron Micrographs of Intact T'Iicelles
Electron Micrographs of Freeze-etch I?.eplicas
Ultracentrifugation of Casein I1icelles
Ca and Phosphate Distribution Discussion
'fEI"ll-).t!:R,V11UHJ� DBFENDEJ:f'r IJRCPEH'l'IBS CF C J0SEI N l'UCELLES
Ultracentrifugation
Voluminosity and Solvation of Casein I'1icelles
5 . 3 Gel Chromatography of Bovine, Caprine and Ovine Casein Micelles
5 . 4 Discussion
PART II ISOLATION AND CHARACTERIZATION OF THE I'1AJOR CAFHINE AND OVINE CAS:EINS AND A COJ."lPARISON 1./ITH THE BOVINE C ASEINS
CHAPT:ER 6 IN'rRODUCTION BOVINE CASEINS
6 . 1 Historical
6 . 2 Identification of the Major Casein
Fractions
28 30
30 32 34
37 37 39
47 54
55 56
56 56 57
Tab l e of Cont ents
(
C ontd .)
�;-CASEIN
.8-C ASEI N
a s -CASEINS 6. 3
6 .4 6 .5 6 .6 6 .7
Genet ic Variant o f Bovine C as eins
I solation of �-Cas e in
Phys i c a l Properti es of K-C as ein Ac t i on. o f Rennin on K-Cas ein
Nature o f th e C arb ohydrat e Res idues in K-C as ein
6 . 8 Amino Ac id C ompo s i tiJn and Primary Struc t ure of K-Cas ein
Page No . 58 61
61 6 3 6 3 64
64 68
6 .9 I s o lation o f #-Ca s e in 66
6 .10 Phys ical Prop erti es of /3-Cas eins 68 6 .11 Amino Ac i d Compos ition and Sequenc e
of /3-C as ein 72
6 .12 �-Case ins 74
6 .13 6 .14 6 .15
6 .16 6 .17
I s o lat i on of as 1 -Cas eins
Phys ical Proper t i e s of a s -C as e ins Amino Ac i d C ompo s ition and Primary Struc tur e of as 1 -C as eins
I-linor a s -Cas eins
Homol o gi es Within the C as eins 6 .1 8 A Pos s ib l e Mechanism of Cas ein
Fho sph0rylation
6 .19 Phylogenetic R e l at i onships of the Bovine Cas eins
75
75 '75
78 80 81 81
83
CASEINS FROM OTHER SPECIES 87
6 .20 C aprine Cas eins 6 .21 Ovine Cas eins 6 .22 Buffalo Cas eins 6 .2 3 Human C as eins 6 .24 Oth er Cas eins
87 89 9 3 93 96
Table of Cont.o�ts (Contd.
)
EXrERI I'1ENrl'AL
7 . 1 7 . 2 7.3 7 • Lj.
7 -5
7.6 7 -7 7 . 8 7. 9
Preparation of Acid Caseins
Polymorphism in Caprine nnd Ovine Casoins
Chromatography of Casein on DEAE- Cellulose
Chromatography of Casein on CM- Cellulose
Polyacrylamide Disc Gel Electro- phoresis
Polyacrylamide .Slab Gel Llectro- phoresis
Gel Electrophoresis in Buffers Containing I'lg
�rotcolytic Degradation of Caseins with Hennet
Holecular .Jeight of Caprine K-Casein
7 . 1 0 f'Tolecular ·,/eight Ang_lysis in 6fi
Guanidine.HCl
Page No.
9 7 9 7
98 98 99 99 1 01 1 01
1 04 1 0 5
1 06
7 . 1 ·1 �lln.ino .:kid Compositions 1 08
7.1 2 �hosphorus 1 1 0
7.1 3 :t.xtinction Coefficients 1 1 0 7.1 4 Viscosity f'1easurements on Co.prine
and Bovine P-Caseins 1 1 1
7 . 1 5 Sedimentation Coefficients 1 1 3
7.1 6 Calcium Sensitivity of Caprine,
Ovine and Bovine Caseins 1 1 3 7 . 1 7 Temperature Dependent Polymeriza-
tion of p-Casein 1 1 4
CASEIN COl"lPOSITION AND ISOLA'riON OF THE Cm'lEONENTS
8 . 1 Chromatography of \·ihole Bovine Casein on DEAE-Cellulose
8.2 Composition of Bovine Casein
1 1 6
1 1 6 1 1 6
Table of Contents (Contd.
)
8.3
8.4 8.5
8.6 8.7 8.8
Chromatography of ,,/hole Caprine Casein on DE/LE-Cellulose
Composition of Caprine Casein Chromatography of \Jhole Ovine Casein on DElLE-Cellulose
Coriposition of Ovine Casein
Polymorphism in the Caprine Caseins Polymorphism in the Ovine Caseins CHAPTER 9 CHARACTERL�N.riON OF CAPRINE CASEINS CAPRINl� K-CASEIN
9.1 9.2
Purification of Caprine K -Casein Molecular Weight of Caprine
K-Cnsein
9.3 Amino Acid Composition of Caprine
9.4 CAFRINE �-CASEINS
9.5 9.6 9-7
9.8 CAPRINE a -CASEIN
s
9.9 9.10 9.11 9.12
K-Casein Discussion
Isolation of Caprine �1- and
�2-Caseins
Molecular Weights of Caprine t3-Cas eins
Amino Acid Compositions of the Caprine �-Caseins and Bovine
�-Casein B Discussion
Isolation of the a -Caseins Molecular Weights of the s
a -Caseins s
Amino Acid Compositions of the
a -Caseins s
Discussion
Page No.
121 124
126 129 131 135 141 141 141 144
146 148 149
149 152
156 160
161 161
165 165 169
C HAPT ER 10 C HJ�J
�
, CTEHI �ii.TION OF THE 11AJOR OVINE C 1\SLINS10. 1 Ovine �<-Cas ein OVI NE {3 -C ASEINS
10.2 10. 3
10.5 OVIN:t; a s -CASEIN B
10.6 10.7 10. 8 10.9
I so lation of Ovin8 {3-C as eins Molec ular We i ghts of Ovine
{3-C as eins
Amino Ac i d C ompos i t i ons of the Ovine {3-C as eins
Disc us s i on
I s olat i on of Ovine as 2-C as e in and as 3- cas ein
Mol ec ul ar i.·le ie;hts of Ovine
a s -C as eins
Amino Ac i d C ompos i t i ons of th e Ovine as -C as eins
D i s c uss ion
CHAPTER 1 1 PHYSIC AL CHARACTERI L:;A.T I ON OF THE C AFRI NE , OVINB 1\ND l30VIN.F CASEINS
1 1.1 1 1.2 1 1.3
1 1.4
U l trac entrifugation
Viscos i ty Heas ur em ents on the C a prine and Bovine p-C as e ins The Effect of Temperat ure on the S ol ubility of the C aprine , Ovine and Bovine p-C a s e ins in t t.e
Pres enc e of CaC12
C alcium S ens i tivity of the C aprine , Ovine and Bovine C as eins
Stab il i z at i on of the Caprine, Ovine and Bovine a s - and
P-Cas e ins in the Pr es enc e 0f
C aC12 by K-Cas eins
Page N o .
172 1?2 1 74 174 176
176 178 179
179 1 82
182 1 85
1 87 1 87 1 89
195
200
206
Table of Contents (Contd.)
CHAPrER 12
PART III
CHAFrEH 13
REF:ERENCES
11.6 Discussion
Page No.
208
A C Ol"lPAHI SON OF
T
HE PROPERTIES OFCASEINS FROM
THE
l"liLK OF SEVEHALSPECIES
12.1 12.2 12.3 12.4
«-Caseins (J-Caseins
a -Caseins
Conclusions s
I'lODELS OF
BOVINE CASEIN l"IICELLE STRUCTUREnND THZI H RELATI ONSHIP TO CAI--RINE AND
213
213 218 223 226
OVTNE CASEIN l"ITCELLES 228
DISCUSSI ON
13.2 13.3 13.4 13.5 13.6.
13.7
Hydrophobic, Electrostatic and Hydrogen Bonding
Role of Disulphide Bonds Colloidal Calcium Phosphate Ccat-Core Models
Internal Structure I·lodels Sub-unit Models
Caprine and Ovine Casein Micelles and their Relationship to the Models of Bovine Casein Micelle Structure
229
229 231 231 232 233 233
235 241
1 .1 1 . 2
4.1
The C ompos i t i on of Ty�ic al Bovine Skim Mi lk Appr oximat e C ompos it ion o f the Serum and Mic e lle 1:-has es of Typic al Bovine Skim Mi lk at 20°C
C ompos ition of Mi lks
4.2 Conc e ntrat i o ns and Ac t iv ities of C at i ons in Ski mmed Mi lk fr om .Animals of Several Spec i es 4 . 3 Vari ation of Cas ein-Pe llet So lvat i on and Dry
Pe lle t \Jeight with Spec i es and C entri fugation T i me
4 . 4 Dist ribution o f Calc iu m and Inor ganic Phosphat e Bet vJeen f'1i ce llar and S erum Phas e s
5 .3
5 • L�
7 . 1 7 .2 7.3 7.4 7-5 7.6 7-7 8.1 8.2 8.3 8.4
Temperat ur e Dep endent Dissoc iati on of C as ein Nic e lles
Re la t i ve D ens i t i es of f''Jilks and Ultrac entri fuge s era
Intrins ic Vis c os ities and Volumino s i t i es of C aprine , Ovine and Bovine Cas e in l''lic e lles S o lvation of C as ein Mic e lles
Stock So lut i ons Working So lut i ons St ock Ge l S o lut i ons
Ac id Gel So lut ion ( pH 4)
Po lyacr ylamide Ge ls C o rtaining J"Ig Standard Prot e ins
Locarte J.�ino Ac id Ana lys er Program C o mpos ition o f Bovine C as ein
C omposition of C aprine C as ein C omposition o f Ovine C as ein
R e lative Elec trophore t ic Mobi li t i e s o f Some Bovine , C aprine and Ovine C as eins in Alkaline
Page No . 2
3 24 26
3 2 3 3 3 7 40
44
46 1 00 1 00 1 02 102 1 03 1 07 1 09 1 20 1 25 1 3 0
Ge ls 1 34
9 .1 Amino Ac id C ompos itions of C aprine , Ovine and Bovine K-C as e ins
9 .2 9.3 9 .4
Mo lec ular Vei ght s o f C aprine and Bovine Cas eins Amino Ac id C o mpos itions of /3-C as e ins
R e lative Nob i lities of C as ein C omponents in th e Pr es enc e and Abs enc e of f'lg
1 47 1 55 1 58 1 64
'rables
(
Contd.)
9.5 Amino 1\cid Compositions of Caprine and Bovine
� -Cas eins 10.1
10.2 11.1 11.2
P�ino Acid Compositions of the Ovine P-Caseins s
Amino Acid Compos itions of the Ovine a s -Caseins Sedimentation Coefficients of Caprine P-Caseins Intrinsic Viscosities of Caprine and Bovine
.8-Cas eins
11.3 Temperature of Half Trans ition Vo.lues for the P-Caseins
11.4 Stabilization of as- and P-Caseins by the
«-Cas eins
12.1 Amino 1\.cid Compositions of K-Cas eins from Different Species
12.2 12.3
Amino Acid Compositions Different Species
Amino Acid Compositions Different Species
of P-Cas eins from
of a -Caseins from s
Page No.
168 177 184 188 194 196 207 217 222 225
FIGURES
Page No . 4 . 1 Alkal ine gel elec trophoresis o f bovine , c aprine
and ovine c as eins
4 . 2 Typic al el ectron mic rographs of shadowed b ovine , 29
ovine and c aprine c asein mic elles 31 4 . 3 Fr e eze-etch e l ectron mic ro grarhs o f the c as ein
5 . 1
mic e l l es in b o vine , ovine and caprine milk Alkal ine gel el ectrophoresis of the cas e ins pre s ent in the ul trac entri fug e s era , ob tained
31
from the milks at di fferent t emperatur es 38 5.2 Reduc ed vis c o s i ty plots for c aprine cas ein
mic e l l es
5-3 Reduc ed vis c o s ity plots for ovine c as e in mic el l es
5 . 4 Reduc ed vis c os ity pl o t s for b ovine c as ein mic el l es
5 . 5 Elu t i on of ovine sub -mic ellar cas ein aggregates
41 42 43
from a Sephadex G-1 0-Sepharos e 4B c olumn at 37°C 49 5 . 6 Alkal ine gel e l ec tropho�esis o: frac ti ons
obt ained by g e l chromat ography of ovine large
cas e in mic e l l e s at 37°C 50
5 . 7 Elut i on of c aprine sub -mi c e l lar c as e in a ggr e gat e s obt ained from a Sephadex G-1 0-Sepharos e 4B
c o lumn at 6°C
5 . 8 Alkal ine gel e l ec trophores is of frac t i ons
obtained by gel chromatography of c aprine smal l
52
c as e in mic e l l e s at 6°C 53
6 . 1 Relative e l e c t rophore t i c mob il i t i e s of the
6 . 2 6 . 3 6 . 4 6 . 5 6 . 6
genetic variants o f b o vine as1 - , P- and «-c as eins
at pH 8 . 6 and pH 3 . 0 59
Frimary s t ruc t ure of b ovine «-c as e in B Primary struc tur e o f b o vine (1-c as ein A2 Primary s t ruc ture of b o vine CXg1 -cas eins
Homo l o gi es in the sequenc es o f b ovine as1- and fJ-c as e in
Fhyl ogeny o f the "gene c ompl exes" formed by the all e l es of the b ovine as 1 -Cn and �-Cn l o c i
The model for the organi z ation o f the as 1 -Cn-P -Cn- K-Cn " c lus t er o f gene s"
65 73 79 82 85 85
Fie;ures (Contd.)
Page No.
6 . 8 N-terminal sequences of bovine and ovine K-casein A glycomacropeptides
6 . 9 Amino acid sequences of ovine and bovine
8 . 1
para- �-caseins
Chromatography of \tJhole bovine casein on DEAE
cellulose
8 . 2 Alkaline gel electrophoresis of whole bovine
8 . 3
casein and the fractions isolated by chromato
graphy on DEAE-cellulose
Chromatography of whole caprine casein on DEAE-cellulose
8 . 4 Alkaline gel electrophoresis of whole caprine casein and the fractions isolated by chromato-
91 9 2 1 1 7
1 1 8 1 22
graphy on DEAE-cellulose 1 23
8 . 5 Chromatography of \vhole ovine casein on DEAE
cellulose
8 . 6 Alkaline gel electrophoresis of whole ovine casein and the fractions isolated by chromato
graphy on DEAE-cellulose
8 . 8
�olyacrylamide zel electrophoresis (pH 8 . 4 ) of samples of cap�ine casein
Polyacrylamide gel electrophoresis at pH 8 . 4
of samples of ovine casein from different breeds
8.9 Polyacrylamide gel electrophoresis at pH 8 . 4 in the presence of Mg of ovine caseins isolated
1 27
1 28 1 32
1 36
from different breeds of sheep 1 38
9 . 1 Chromatography of caprine K-casein on a CM
cellulose column
9 . 2 Alkaline gel electrophoresis of purified caprine
K-casein
9 . 3 Acid gel electrophoresis of purified caprine K-casein
9 . 5
l''Iolecular weight calibration curve obtained using a Sephadex G-1 00 column
Ch::r:'om2.toe;raphy of crude caprine p2-casein on CI'1-c ell ulos e
1 42 1 43 1 43 1 45 1 50
fic;ures ( C ontd .
)
Page No . 9 . 6 Alkal ine gel e l e c trophores is o f the c aprine
p -c as eins in the abs ence and pres enc e of MG
9 . '7 A typical run used t o calibrat e the mol ec ular weicht c o lumn
9 . 8 Mo l ecular weie;ht cal ib ration curve obtained
1 51 1 53
us ing a Sepharos e 6B c o lumn 1 54
9 . 9 Amino ac id analysis chr omat ogram ob tained for c aprine p2- c as ein ·us ing a Loc art e
Hk.IV
analys er 1 5'7
9 . 1 0 Alkal ine gel elec trophores i s o f pur i fi ed c aprine as -cas ein and purifi ed b ovine as 3-
c as ein in the pre s enc e and ab s enc e o f Mg 1 62 9 . 1 1 Chrom�t ography o f a s ample c ontaining the major
capr ine a - c as ein and b ovine - S a SI �-c as ein B on the molecular weight c o lumn to c ompar e their
mo l ecular wei ght s 1 66
1 0 . 1 Alkal ine gel e l e c trophor e s i s o f purified ovine K-cas ein and the effec t of r ennet on this
frac t ion
1 0 . 2 Alkal ine gel e l e ctrophores is o f the puri f i ed ovine P-c as eins in the ab s enc e o f pr es enc e o f Mg
1 0 . 3 Chromat ography o f ovine as 3- c as e in on DEAE-
c e llulos e
1 0. 4 Alkaline g e l el ec trophor esis o f the ovine
1 1 . 1 1 1 . 2 1 1 . 3 1 1 . 4
cxs - c as eins in the abs enc e and pr es enc e o f I'Ig Reduc ed vis c o s i ty plots for c aprine p1 - c as ein R educ ed vis c o s ity pl ots for c aprine p2-cas ein Reduc ed vis c o s i ty plots for bovine p -c as ein A1 Th e eff ect o f t emperature and ionic strength on the t urb i dity o f c aprine p1 -cas e in
s olut i ons
11 . 5 The effect of temperature and i onic s tr ength on
1 73
1 75 1 80
1 81 1 90 1 91 1 92
1 97
the turb idity o f c aprine p2-c as ein s o luti ons 1 98 1 1 . 6 The effect o f t emperature and i onic s tr ength
on the turb idity o f b ovine p-cas ein B s ol utions 1 99 1 1 . 7 C alc ium s ens i �ivity o f the c aprine ��c a�eins at
37°C 201
:B,ip;ures (Contd.
)
'11.8 Calcium sensitivity of the caprine, ovine and bovine �-caseins at 37°C
Page No.
202 1'1.9 Calcium sensitivity of the as-caseins at 37°C 20L�
'11.'10 Calcium sensitivity of the caprine, ovine und
bovine a s -caseins at 37°C 205
