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1.
Grainger Reid J. Ko Samuel Koslov Eugene Prokop Ales Tanner Robert D. Loha Veara 《Applied biochemistry and biotechnology》2000,84(1-9):761-768
Human insulin in zinc suspension was used as a model protein to test the effect of shear on the settling rate of proteins,
a possible inference for protein denaturation. The rate of settling was determined directly in a spectropho-tometer. Shear
effects are important in retaining the activity of proteins and are present in bubble, foam, and droplet protein fractionation
processes. A sim pletest, such as that conducted here, mayeven be useful for monitoring changes in protein structure caused
by commercial shipping of the protein. The settling ratefor insulin was continously monitored in theoriginal bottle by spectrophotometric
absorbance changes as a function of time. A settling curve was determined following each shear experiment, which included
shaking the “worked” insulin solution in a vortex mixer for different lengths of time. It was determined, when comparing long
shaking times with short ones, that the initial settling rate was less for the long-term shaking of the insulin samples and
greater for the short-term shaking. The secondary effects of light and heat, along with shaking, a pparently did not produce
differences from shaking alone. 相似文献
2.
Veara Loha Aleš Prokop Liping Du Robert D. Tanner 《Applied biochemistry and biotechnology》1999,79(1-3):701-712
Foam fractionation isone of the low operating-cost techniques for removing proteins from a dilute solution. The initial bulk
solution pH and air superficial velocity play an importantrole in the foam-fractionation process. Denaturation of proteins
(enzymes) can occur, however, during the foamfractionation process from the shear forces resulting from bursting air bubbles.
At the extreme bulk solution pHs (lower than 3.0 and higher than 10.0), the en zymatic activity of cellulase in the foamate
phase drops significantly. Within these two pH boundsan increase in the air superficial velocity, Vo, and a decrease in the bulk solution pH leads to a decrease in the separation ratio (SR), defined as theratio of the protein
concentration in the foamate to the protein concentration in the residue. On the other hand, an increase in Vo provides a higher foamate-protein recovery. The process efficiency is defined as the product of foamate-protein recovery
times the SR times the cellulase activity. The optimal operating condition of the cellulase foamfractionation process is taken
into account at the maximum value of the processefficiency. In this study, that optimal condition is atan air superficial
velocity of 32 cm/min and a bulk-solution pH of 10.0. At this condition, the recovered foamate is about 80% of the original
protein mass, the SR is about 12, and the en zymatic activity is about 60% of the original cellulase activity. 相似文献
3.
Fermentation broth normally contains many extracellular enzymes of industrial interest. To separate such enzymes on-line could
be useful in reducing the cost of recovery as well as in keeping their yield at a maximum level by minimizing enzyme degradation
from broth proteases (either the desired enzymes or the proteases could be removed selectively or both removed together and
then separated). Several large-scale separation methods are candidates for such on-line recovery such as ultrafiltration,
precipitation, and two-phase partitioning. Another promising technique for on-line recovery is adsorptive bubble fractionation,
the subject of this study. Bubble fractionation, like ultrafiltration, does not require contaminating additives and can complement
ultrafiltration by preconcentrating the enzymes using the gases normally present in a fermentation process. A mixture of enzymes
in an aqueous bubble solution can, in principle, be separated by adjusting the pH of that solution to the isoelectric point
(pI) of each enzyme as long as the enzymes have different pIs. The model system investigated here is comprised of three enzyme
separations and the problem is posed as the effect of pectinase (a charged enzyme) on the bubble fractionation of invertase
(a relatively hydrophilic enzyme) from α-amylase (a relatively hydrophobic enzyme).
The primary environmental variable studied, therefore, is the pH in the batch bubble fractionation column. Air was used as
the carrier gas. This prototype mixture exemplifies an aerobic fungal fermentation process for producing enzymes. The enzyme
concentration here is measured as total protein concentration by the Coomassie Blue (Bradford) solution method (1), both as a function of time and column position for each batch run. Since, from a previous study (2), it was found that invertase and α-amylase in a two-enzyme system can be partially separated in favor of one vs the other
at two different pHs (pH 5.0 and 9.0) with significant separation ratios, emphasis is placed on the effect of pectinase at
these pHs. In this study, the addition of pectinase reduced the total separation ratio of the α-amylase-invertase mixture
at both pHs. 相似文献
4.
The effect of fermentation (retting) time and harvest time on kudzu (Pueraria lobata) fiber strength
Uludag Sibel Loha Veara Prokop Ales Tanner Robert D. 《Applied biochemistry and biotechnology》1996,57(1):75-84
Applied Biochemistry and Biotechnology - The noncommercial kudzu plant has been growing wild in the southern United States since the 1930s. In this article, the kudzu fibrous vine is investigated... 相似文献
5.
Samuel Ko Veara Loha Liping Du Ales Prokop Robert D. Tanner 《Applied biochemistry and biotechnology》1999,78(1-3):501-510
Water droplets or mist occur naturally in the air at seashores. These water droplets carry inorganic and organic substances
from the sea to the land via the air, creating fertile land in sandy coastal areas (1). The same phenomenon occurs in an air-fluidized bed bioreactor (2). In an air-fluidized bed reactor, proteins can be transferred from the bioreactor semisolid bulk phase to an enriched droplet
phase. This protein transfer process (droplet fractionation) can be experimentally simulated by shaking a separatory funnel
containing a dilute solution of a given protein, which can be an enzyme like invertase. The created droplets become richer
in invertase (protein) than that of the original dilute solution. The droplets can then be coalesced by tranpping them and
recovering the concentrated protein in the new liquid phase. Typically, in such a droplet fractionation process a collected
enzyme can be degraded in its ability tocatalyze a chemical reaction. In this article, we explore whether the initial solution
pH control variable can be adjusted to minimize the decrease of enzyme activity in this process. The protein droplet recovery
problem is one in which the recovered amount of desired protein (enzyme) in the droplet is maximized, subject to the minimization
of the enzyme activity loss. The partition coefficient, which is the ratio between the protein concentration in the droplets
and the residual solution, is maximized at approx 4.8 and occurs at pH 3.0. Here, the partition coefficient for invertase
decreases as the initial solution pH increases, between pH 3.0 and 8.0. Interestingly, the initial solution surface tension
seems to be inversely proportional to the partition coefficient. The partition coefficien treachesa maximum value at a surface
tension value of approx 63 mN/m at pH 3.0. The enzymatic activity of the initial, the residual, and the droplet solutions
all decrease as the bulksolution pH increases. Adecrease of enzymatic activity was observed in the residual bulk solution
when compared with that in the initial bulk solution at all pH levels. Also, up to 90% of the invertase activity was lost
in the droplets when compared to the initial bulk solution. 相似文献
6.
Eiamwat Jirawat Loha Veara Prokop Aleš Tanner Robert D. 《Applied biochemistry and biotechnology》1998,(1):559-567
The aqueous protein solution from kudzu(Pueraria lobata) vine retting broth, without the addition of other surfactants, was foam-fractionated in a vertical tubular column with multiple
sampling ports. Time-varying trajectories of the total protein levels were determined to describe the protein behavior at
six positions along the 1-m column. The lowest two trajectories of this batch process represented a loss of proteins from
the bulk liquid and tended to merge and decay together in time; the other trajectories displayed a gain in proteins in the
foam phase. These upper column port protein concentration trajectories generally increased in time up to 45 min, followed
by a decrease, reflecting the removal of proteins from the column ports. The foam became dryer as it passed up the column
to the top port. The protein concentration was about 5–8×higher in the top port foam than in the initial bulk solution, mainly
as a result of liquid drainage from the foam along the column axis. This concentration increase in the collected foam was
dependent on the initial pH of the bulk solution. The mol-wt profile of the proteins in the concentrated foam effluent was
determined by one-dimensional gel electrophoresis. An analysis of the gel electropherograms indicated that the most abundant
proteins could be cellulases and pectinases. 相似文献
7.
Ko Samuel Loha Veara Prokop Ales Tanner Robert D. 《Applied biochemistry and biotechnology》1998,(1):547-558
The major sweet potato root protein, sporamin (which comprises about 80–90% of the total protein mass in the sweet potato)
easily foams in a bubble/foam-fractionation column using air as the carrier gas. Control of that foam fractionation process
is readily achieved by adjusting two variables: bulk solution pH and gas superficial velocity. Varying these parameters has
an important role in the recovery of sporamin in the foam. Changes in the pH of the bulk solution can control the partitioning
of sporamin in the foam phase from that in the bulk phase. A change in pH will also affect the amount of foam generated. The
pH varied between 2.0 and 10.0 and the air superficial velocities (V0) ranged between 1.5 and 4.3 cm/s. It was observed in these ranges that, as the pH increased, the total foamate volume decreased,
but the foamate protein (mainly sporamin) concentration increased. On the other hand, the total foamate volume increased significantly
as the air superficial velocity increased, but the foamate concentration decreased slightly. The minimum residual protein
concentration occurred at pH 3.0 and Vo = 1.5 cm/s. On the other hand, the maximum protein mass recovery occurred at pH 3.0 and at Vo = 4.3 cm/s. 相似文献
8.
Tanner Robert D. Ko Samuel Loha Veara Prokop Ales 《Applied biochemistry and biotechnology》2000,84(1-9):1079-1086
It has previously been shown that a droplet fractionation process, simulated by shaking a separatory funnel containing a dilute
protein solution, can generate droplets richer in protein than present in the original dilute solution. In this article, we
describe an alternative method that can increase the amount of protein transferred to the droplets. The new metho uses ultrasonic
waves, enhanced by a bubble gas stream to create the droplets. The amount of protein in these droplets increases by about
50%. In this method, the top layer of the dilute protein solution (of the solution-air interface) becomes enriched in protein
when air is bubbled into the solution. This concentrating procedure is called bubble fractionation. Once the protein has passed
through the initial buildup, this enriched protein layer is transferred into droplets with the aid of a vacuum above the solution
at the same time that ultrasonic waves are introduced. The droplets are then carried over to a condenser and coalesced. We
found that this new method provides an easier way to remove the protein-enriched top layer of the dilute solution and generates
more droplet within a shorter period than the separatory funnel droplet generation method. The added air creates the bubbles
and carries the droplets, and the vacuum helps remove the effluent airstream from the condenser. The maximum partition coefficient,
the ratio of the protein concentration in the droplets to that in the residual solution (approx 8.5), occurred at pH 5.0. 相似文献
9.
Du Liping Loha Veara Tanner Robert D. 《Applied biochemistry and biotechnology》2000,84(1-9):1087-1099
A simple staged model for the protein foam fractionation process is proposed in this article. This simplified model does not
detail the complex foam structure and gas-liquid hydrodynamics in the foam phase but, rather, is built on the conventional
theoretical stage concept considering upward bubbles with entrained liquid and downward liquid (drainage) as counter-current
flows. To simulate the protein concentration distribution in the liquid along the column by the model, the bubble size and
liquid hold-up with respect to the position must be known, as well as the adsorption isotherm of the protein being considered.
The model is evaluated for one stage by data from the semibatch foam fractionation of egg albumin and data from the continuous
foam fractionation of bovine serum albumin. The effect of two significant variables (superficial gas velocity and feed protein
concentration) on enrichment is well predicted by the model, especially for continuous operation and semibatch operation when
initial concentration is high. 相似文献
10.
Tanner Robert D. Parker Tobias Ko Samuel Ding Yuoing Loha Veara Du Liping Prokop Ales 《Applied biochemistry and biotechnology》2000,84(1-9):835-842
Foam fractionation is a cost-effective process that uses air to extract protein from a liquid (in this case “crude” dilute
egg-albumin solution). This article deals with how the void fraction (fraction of air in the aerated solution) of foam is
affected by heat denaturation of the protein. A 2-mm glass tube was used to sample the foam-liquid interface fluid in a 35-mm-diameter
column in order to detect small changes in void fraction and foam production, which are not easily detected directly from
the bulk foam. The main control variablein this study was the protein solution preheating time. As the preheating time increased,
the initial void fraction in the column decreased. The initial void fraction of the undenatured solution ranged from about
0.73 to 0.80, and the void fraction for significant preheating times of 5 min ranged from approx 0.68 to 0.72. Furthermore,
the period of foam production increased from 5 to 7 min for undenatured proteins in solution to as long 15 min for 5-min preheated
solutions. Side-port sampling through a small capillary tube has the potential to be used as a rapid and inexpensive way to
determine the level of protein denaturation by directly determining the void fraction and then estimating the effect of denaturation
from a protein denaturation calibration curve of the void fraction. 相似文献
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