Crystalline Urease Preparation of Meal from Jack Beans J. STANLEY KIRKAND J. B. SUMNER Department of Physiology a n d Biochemistry, Cornell University Medicdl School, Ithaca, N. Y I t was necessary to construct a bolting box, shown in Figure 1. The meal delivered from the mill passes into w e end of this box, and the fine material is sifted through a No. 14 stretched silk to a fine pm&r without lieatbolting cloth and then falls from ing and without tlie introduction a hole in the bottom of the Ins of lieavy metals, such as copper. into beaker A . The material Although it is not yet certaiii which is t o o c o a r s e to pass what conditions are requisite for through the cloth leaves the box growing beans rich in ureasc, t,hv through a wooden tube a t the a u t h o r s have succeeded, after other end and collects in beaker several failures, in learning hoa R, and is put through the mill to grind jack beans properly. a g a i n . The box is suspended Tlie beans must b r thoroiighl~ from an iron frarnework by four d r y before grinding. This iron hack-saw b l a d e s and is can be attained by spretidiliy shaken 550 times a minute by atthem out in a thin layer on ti taelirnent to ail eccentric r u n by clean blanket and leaving for alx~ltfromapulleyonthepolisliabout 2 weeks in a room heated ing liead. during t,he daytime t o 75" 1;. ..As drlivcred from the nmm(23.9" C.). Tlie beaiis are theii hrokeii into a meal about. as coarse as chickel, fetd l,y puttili8 fticturer, the iiiill had itii q m i u l g in the flange above ihe spout., them once through a large criffee rriill equipped with steel and from this opening niucli of the meal escaped doring grindhurrs. Since the hulls are devoid of urease, they are re- ing. This loss of inaterial was prevented by placing about the moved at this &age, as far as practicable, either by picking liurrs and within the flange a thin strip of Russian iron, 4 hy "5 inches. Figure 2A sliows the grinding surface of tlie lower porcelain burr supplied with the inill. The smooth rims a t the peripliw y of the burrs caused the meal to cake and t o heat and this heating partly inactivated the urease. Therefore grooves were ground in tlie lower burr and were continued in the upper burr to the periphery by means of a Bakelite-Carborunduin disk attached to an electric niotor. Tlie burrs thus rround are shown in Figures 2B and C. This has greatly increased tlie efficiency of the mill and the sharp grinding siirfaces have not so much tendency to heat. Ilowever, ~~~~~~. during grinding the burrs should not be screwed down tightly or some heating will result. FIOUHE 1. MILLron GRINDING JACKBRANS With the inrprovements described above, it is pssii>le to out by Irund, or by firat sifting tlie fine material tlirough Ihtain jack-bean meal which is fully as satisfactory as any cheese cloth and then allowing the coarse material to fall meal obtained from any commercial fimi. The yield of m a l through an air blast from an electric fan and into a box. is approximatcly one kilograni an hour. The lielit hulls are blown awav.
K O1LI)ER to rhtain urease cr,vstals (I..?) iii gooil yield,
The claim inude in 1926 that the oclahedral globulirt crystals, which can be reudily oblained from jack-bean meal, are identical with 1h.e enzyme, urease, uxis at first Feeeked u d h considerable skepticisni. Hecent work by Sumner and h.is cnllahrators, as well us the work by Northrop 011 crystalline pepsin,, has done much to dispel this. This urticle describes a srnall mill for grinding juck hearis lo a nieul suilable for preparing urease crystals. Since the burrs of the inill w e of porcelaiir, while the other ~ W L Sore of iron, tlzerc is no possibility of poison,ing the enzyine by lhe introduction i n h the meal of copper or m y nthcr iiiidr.siru,/~ieheavy metal. The griridiriy is curried out in such a nc(xniier us lo ensure a niinirnul o n i o i i r i l of deslrirction of the enzyme by h d i n g .
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.,
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leather belt. In order to reduce tllc speed tiJ 10.5 r. p. in., a rechiaing head, equipped with variable diameter pirlleys, was insert,ed betwecn the inotor and the mill.
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" FIGunE 2.
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C n r K o I N G SunFACW OF B O t i H S
Botturo burr ea supdied with mill, B . Hutturn bufi a8 rndified by grindin.. C. Tog bum 88 modified by priodina.
April, 1932
INDUSTRIAL AND ENGINEERING CHEMISTRY
AAcr,NOWLEDGNEXT The authors wish to acknowledge their indebtedness to the Heckscher Foundation of Cornel1 University for financial aid without which this work would have been impossible, and to the A. H. Thomas Company for their generous cooperation. ~
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LITERATURE CITED (1) Summer J. B., J. B i d . Chem., 69,436 (1926).
!i; ~~~~~~; 5: i:;zt:, 673q)~~D,~ B,,2~ ( B&,,L, ~ ~ ~ ~ ~ j , sumner, J. B,, and ~ d them., , 76, 149 ( 1 9 ~ ) . (4)
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(6) Sumner, J. B., and Holloway, R G., Ihid., 79, g@(12928). RECXIVED January 30, 1932. -_.__
Application of Duhring’s Relatio Solubilities
4
R. L. HARRIS,University of Delaware, Newark, Del.
I
N 1878 Duhring announced It has been found that Duhring’s relation f Kl’ = any function of M where (I and K = constants an by can be used to predict the solubilities of nonT = temperature the use of which the vapor M solubility in moles Per hydrated, inorganic salts in water at various pressure of a substance can be 1000 grams of water temperatures. Results are obtained of a n accalculated with reasonable accuracy often as good as the data themselves and Temperature may Or may not be curacy. iilthough the rule has absolute* Then, if for two salt been expressed mathematically rarely poorer than 5 per cent, even though but solutions the solubility he chosen byDuhringand Others (3’ / “ i l o ) , two points f a r apart on fhe solubility curve haw the same, the calculation is generally made been determined experimentally . graphically. If the t e m p e r a f(Md = f(Md, and CI + tures a t which one substance exK I T I = CA KL7’2 erts certain vapor pressures be plotted against the temperatures a t which a reference substance exerts the same vapor or the graph of TI vs. Tzwill be a straight line. Many attempts have been made to formulate the equation pressures, the points are found to lie nearly upon a straight line. for the variation of the solubility of electrolytes with temTherefore, if the vapor pressure of a substance be known a t two points, a straight line may be drawn in accordance with perature, but the problem is complicated by the ionization Duhring’s relation, the complete vapor-pressure data for a of the electrolyte and by the possible hydration of the ions. reference substance having been taken from the literature. Some have introduced correction factors to allow for these From this Diihring line the entire vapor-pressure curve of effects, but equations so modified are usually made so involved that they have lost their practical utility. The ideal the substance in question may easily be calculated. solubility equation is derived in the same way as is the Duhring’s relation has been used in recent years by a number of investigators. Badger and McCabe ( 1 ) and Clausius-Clapeyron equation, and is generally deduced for Walker, Lewis, and McAdams ( 1 1 ) call attention to its use organic solutions on the assumption that Raoult’s law a p in evaporator design and in determining the latent heat plies. Such is the case for solutions of naphthalene in or(5) has shown that in of vaporization of solutions and pure liquids (9). It has also ganic solvents, and Hildebrand 1 been used in finding the boiling point us. composition curves these instances the graph of os. log ilr, (where T is of solutions of organic solvents, and the vapor pressure the absolute temperature and N z is the mole fraction of curves of solutions of electrolytes in water (2). Aside from solute) are .straight lines. However, Hildebrand further its use in predicting vapor-pressure data, Duhring’s rela- shows (6) that, in the case of solutions of electrolytes in tion has been applied by Porter (12) to the estimation of water, the simple relation no longer obtains, and the modified the change in viscosity of liquids with changing tempera- equation, which is even then admittedly not exact, becomes ture. too unwieldly to be of value in predicting solubilities. Duhring’s relation, however, can be easily applied, and results THEORETICAL DISCUSSION are obtained which are within the accuracy ordinarily reAlthough White (13) has since shown it to be compatible quired in engineering calculations. Another relation which has been of service in predicting with the integrated form of the Clausius-Clapeyron equation, Diihring’s relation was first discovered as an empirical vapor pressures is that of White (13): The graph of 1 us. 1 T2 rule suggested by the close similarity of vapor-pressure curves. But it has been shown by Hildebrand (4) and others that the where TI and Tz are absolute temperatures a t which two ideal case of solution is quite analogous to that of vaporiza- substances have equal vapor pressures, is a straight line. tion. It would therefore seem plausible that Duhring’s re- Obviously in the case of ideal solubility above referred to, lation should apply to solubility curves in general. More- where over, the solubility curves of salts in water, especially of salts = log .V? + ( ‘ T of the same chemical nature, are similar in shape; so for this reason also Duhring’s relation should be expected to White’s rule will apply exactly. This relation has, therefore, more theoretical justification than Duhring’s as yet apply. Mathematically speaking, for the relation to apply to enjoys, but the actual results of its application are somesolubility curves, it is necessary only that they be of the times hardly as accurate. Almost no deviation from the form: rule was noted when the nitrates of caesium, rubidium, lead,
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