Relevant Concentrations Of Cu Research Articles

Impact of copper and zinc oral chronic exposure on Carniolan honey bee survival and feeding preference.

Honey bees are important plant pollinators and honey producers. Contamination of the environment with metals can lead to a decline in honey bee populations. Copper (Cu) and zinc (Zn) salts are commonly used as fungicides and foliar fertilizers. In this study, we investigated the effects of 10-day chronic oral exposure to different concentrations of Cu (CuSO4) and Zn (ZnCl2) on survival and feeding rates of Carniolan honey bees in laboratory conditions. We found that mortality in honey bee workers increased in a concentration-dependent manner and that Cu (lethal concentration [LC50] = 66 mg/l) was more toxic than Zn (LC50 = 144 mg/l). There was no difference in the feeding rate of Cu-treated bees for the different concentrations tested, but the feeding rate decreased with the increase in Zn concentration. To determine feeding preference or avoidance for Cu and Zn, we conducted 2-choice 24-h feeding experiments. We demonstrated that honey bees preferred Zn-containing solutions compared to the control diet. A two-choice experiment with Cu showed a tendency for honey bees to be deterred by Cu at high concentrations; however, it was not statistically significant. In summary, our results suggest that honey bee workers may suffer adverse effects when exposed to ecologically relevant concentrations of Cu and Zn.

Photosynthetic and antioxidant responses of Ankistrodesmus flexuosus and Curvastrum pantanale to environmentally relevant copper concentrations

AbstractSince high concentrations of copper (Cu) are known to negatively affect algae, we investigated the effect of environmentally relevant concentrations of Cu on the metabolism and photosynthesis of microalgae. We investigated the photosynthesis and antioxidant responses of two green microalgae, Ankistrodesmus flexuosus and Curvastrum pantanale, to free Cu (1.7 nM–589.0 nM Cu2+), which included environmentally significant values (1.7 nM–21.4 nM Cu2+). The microalgae had similar growth rates at low Cu2+, but C. pantanale had higher growth rates at 7.4 and 21.4 nM Cu2+, and a higher Chl a/b ratio at 1.7–21.4 nM Cu2+. The Fv/Fo of A. flexuosus was not altered by Cu, whereas its relative maximum electron transport rate (rETRm) began to decrease at 7.4 nM Cu2+. The Fv/Fo and rETRm of C. pantanale increased at 21.4 nM Cu2+. The non‐photochemical quenching (NPQ) that was actively dissipated [Y(NPQ)] in A. flexuosus increased with Cu increase, whereas at 589.0 nM Cu2+, the NPQ of C. pantanale decreased and its passive energy dissipation [Y(NO)] increased. C. pantanale had higher photosynthesis at 1.7–21.4 nM Cu2+. Superoxide dismutase (SOD) activity increased in both microalgae at high Cu concentrations, at 21.4 nM Cu2+ for A. flexuosus, and at 589.0 nM Cu2+ for C. pantanale. Thus, environmentally relevant Cu concentrations can favor the survival of tolerant microalgae species, hence shifting the diversity of aquatic biota.

Copper and zinc accumulation, distribution, and tolerance in Pistia stratiotes L.; revealing the role of root caps

Pollution by potentially toxic trace metals, such as copper or zinc, is global. Both Cu and Zn are essential microelements, which in higher concentrations become toxic. The aquatic plant Pistia stratiotes(L. has great potential for phytoremediation. Also, it has an unusually large and easily detachable root cap, which makes it a suitable model for studying the potential role of the root cap in metal uptake. Plant response to environmentally relevant concentrations of Cu (0.1, 0.3, and 1 μM) and Zn (0.3, 1, and 3 μM) was investigated with the aim of studying their interaction and distribution at the root tissue level as well as revealing their tolerance mechanisms. Changes in the root anatomy and plant ionome were determined using light and fluorescence microscopy, ICP-MS, and μXRF imaging. Alterations in photosynthetic activity caused by Cu or Zn excesses were monitored by direct imaging of fast chlorophyll fluorescence kinetics (OJIP). Fe and Mn were preferentially localized in the root cap, while Ca, Cu, Ni, and Zn were mainly in the root tip regardless of the Cu/Zn treatment. Translocation of Cu and Zn to the leaves increased with higher doses, however the translocation factor was the lowest in the highest treatments. Measurements of photosynthetic parameters showed a higher susceptibility of electron transport flux from QA to QB under increasing Cu than Zn supply. This, along with our findings regarding the root anatomy and the differences in Ca accumulation and distribution, led to the conclusion that P. stratiotes is more effective for Zn remediation than Cu.

Effects of elevated temperature and copper exposure on the physiological state of the coral Galaxea fascicularis

The co-occurrence of elevated seawater temperature and local stressors (heavy metal contamination) affects the ecophysiology of phototrophic species, and represents a risk to the environmental quality of coral reefs. Therefore, we investigated the effects of both Cu alone and Cu in combination with elevated temperature (ET) on the physiology of the coral Galaxea fascicularis, and measured the parameters related to the photo-physiology and oxidative state. G.fascicularis is one of the dominant coral species in the South China Sea which exhibits strong adaptability to environmental stress. We exposed the common coral species G.fascicularis to a series of environmentally relevant concentrations of Cu at 29 °C (normal temperature, NT) and 32 °C (elevated temperature, ET) for 96 h. Single polyps were used in the experiments, which reduced individual variability when compared to the coral colonies. The results suggested that: i) Cu or ET had significant negative effects on the actual operating ability of photosystem Ⅱ (PSII), but not on the maximal chlorophyll fluorescence in darkness (Fv/Fm). ii) Symbiodiniaceae density was significantly reduced by high Cu concentrations, for Cu-NT and Cu-ET, a high concentration of Cu (40 μg/L) significantly impacted Symbiodiniaceae density, causing a 75.4% and 81.0% decrease, respectively. iii) the content of malondialdehyde (MDA) in coral tissues increased significantly under Cu-ET. iv) a certain range of copper concentration (25–30 μg/L) increased the pigment content of the Symbiodiniacea. Our results indicated that the combined stressors of Cu and ET made the coral tissue sloughed, caused the coral tissue damaged by lipid oxidation, reduced the photosynthetic capacity of the Symbiodiniacea, and led to the excretion of Symbiodiniacea.

Antagonistic effects of copper and microplastics in single and binary mixtures on development and reproduction in the freshwater cladoceran Daphnia carinata

The combined effect of microplastics (MPs) and other contaminants such as trace metals is largely unknown although MPs can act as a vector for other contaminants. The present study investigated the impact of a single and mixture of MPs and a common trace contaminant, copper (Cu) on the Australian freshwater cladoceran Daphnia carina . No acute value was recorded when D. carinata was exposed to clear polyethylene size of 1–10 μ m with the concentration ranging from 5, 25, 50, 100, 200 and 300 mg/L during 48 h of exposure. D. carinata showed a tendency to utilize MPs from the surrounding environment to prolong their life when the food was scarce. When D. carinata were exposed to environmentally relevant concentrations of Cu: 1 and 3 μ g/L or MPs concentration of 0.25 and 1 mg/L for 21 days, no effects on reproduction was recorded. The impacts of Cu and MPs on molting frequency in the mixture treatments were less than in the single contaminant treatments. D. carinata juveniles were more sensitive to Cu than the adults regardless of the presence or absence of MPs. The findings highlight the importance of clarifying the interaction between traditional and contaminants of emerging concern for effective risk assessment. • Microplastics (MPs) could prolong the survival of D. carinata when food was scarce. • Reproduction in D. carinata was not affected by exposure to MPs and Cu individually. • D. carinata juveniles were more sensitive to Cu than adults. • Effects of Cu on moulting of D. carinata was smaller in the presence of MPs.

Effects of co-exposure to copper and humic acids on microalga Chlorella vulgaris: growth inhibition, oxidative stress, and extracellular secretion

ABSTRACT Heavy metals were typical contaminants in aquatic ecosystems, while their effects on the biotoxicity and metabolism of algal cells in the presence of organic ligands were still unclear. In this study, the contrasting effects of Cu and humic acids (HA) on the growth inhibition, oxidative stress and extracellular secretion of microalga Chlorella vulgaris were studied at environmentally relevant concentrations of Cu (0~2 mg/L) and HA (0~20 mg/L). Results showed that, with increased Cu addition, the algal growth rate decreased while concentrations of superoxide dismutase and malondialdehyde increased showing evident growth inhibition and oxidative damage in the sole presence of Cu. However, the presence of HA could significantly alleviate the Cu-induced toxicity damage, and higher concentrations of HA exhibited greater alleviation efficiencies. Fluorescence spectroscopy combined with flow field flow fractionation revealed that secretion of 50 kDa~0.45 μm of extracellular protein-like substances was the critical fractions responsible for the biotoxicity alleviation. Analysis of Cu contents within extracellular polymeric substance (EPS) matrix showed that not only the secretion amounts but also the acquisition capacities of EPS matrix decreased due to the addition of HA. This study benefited an in-depth understanding toward the toxicity of heavy metals to aquatic microorganisms in natural waters that contained abundant organic ligands.

Acute exposure to environmentally relevant concentrations of copper affects branchial and hepatic phosphoryl transfer network of Cichlasoma amazonarum: Impacts on bioenergetics homeostasis

The toxic effects of copper (Cu) are linked to dysfunction of metabolism and depletion of adenosine triphosphate (ATP). Nevertheless, the effects related to phosphoryl transfer network, a network of enzymes to precise coupling of the ATP-production and ATP-consuming process for maintenance of bioenergetic, remain unknown. Therefore, the aim of this study was to determine whether the phosphoryl transfer network could be one pathway involved in the bioenergetic imbalance of Cichlasoma amazonarum exposed for 96 h to environmentally relevant concentrations of Cu found in Amazonia water around mines. Branchial mitochondrial creatine kinase (CK) activity was significantly lower in fish exposed to 1500 μg/L Cu than in the control group, while branchial cytosolic CK activity was significantly greater. Branchial (exposed to 750 and 1500 μg/L Cu) and hepatic (exposed to 1500 μg/L Cu) pyruvate kinase (PK) activity was significantly lower in fish exposed to Cu than in the control group. Branchial and hepatic ATP levels were significantly lower in fish exposed to 1500 μg/L than in the control group. Branchial reactive oxygen species (ROS) and lipid peroxidation (LPO) levels were significantly higher in fish exposed to 750 and 1500 μg/L Cu compared to control. Hepatic ROS and LPO levels were significantly higher in fish exposed to 1500 μg/L than in the control group. Branchial and hepatic Cu levels were significantly higher in fish exposed to 1500 μg/L compared to other groups. Exposure to 750 and 1500 μg/L Cu impairs bioenergetics homeostasis, which appears to be mediated by ROS overproduction and lipid peroxidation.

Chicken thalamic injury induced by copper (II) or / and arsenite exposure involves oxidative stress and inflammation-induced apoptosis.

Copper (Cu) is a toxic substance of heavy metals, and arsenic (As) is a toxic substance of metalloids. They all cause oxidative stress and have been widely studied in recent years. Studies have reported that Cu and As can cause inflammation in chicken brain tissue. To assess the toxicological effects of Cu and/or As chronic exposure on chicken thalamus, we used toxicologically relevant concentrations of Cu and As in the chicken diet for 12 weeks. By comparative analysis, we found that higher malondialdehyde (MDA), total antioxidant capacity (T-AOC), and proinflammatory mediator (NF-κB) were observed in the Cu and/or As co-exposed group, indicating that oxidation stress and inflammation are produced. In addition, we also observed mitochondrial kinetics and the generation of apoptosis. These include the gene and protein expression levels of Drp1, Opa1, Mfn1, Mfn2 and Bcl-2, Bax, p53. In conclusion, we believe that in the chronic poisoning of Cu and/or As, inflammation occurs in the chicken thalamus, causing oxidative stress and mitochondrial kinetics, which eventually leads to apoptosis.

A review of chemical speciation techniques used for predicting dissolved copper bioavailability in seawater

Environmental contextCopper (Cu) is a metal of ecotoxicological concern in contaminated coastal areas. Cu present as the free ion is considered the most bioavailable fraction of the metal, and there is a need for the correct measurement or estimation of free Cu-ion concentrations in seawater. I review studies that have combined a biological measure of Cu bioavailability with chemical speciation measurements, and critically assess the ability of current methods to predict Cu bioavailability in contaminated coastal ecosystems. AbstractCopper (Cu) is an essential metal, but it is also toxic at concentrations reached in polluted coastal areas. In seawater, the speciation of this metal is largely controlled by the presence of dissolved organic matter (DOM), which binds Cu ions decreasing the concentration of inorganic and free forms of the metal. This is important to aquatic life, given that the bioavailability of dissolved metals is generally expected to be determined by the free ion concentration according to bioavailability models such as the free ion activity model and biotic ligand model (FIAM/BLM). The analytical determination of free metal concentrations in seawater is a challenging task that is needed (in combination with toxicity tests or other means of testing bioavailability) in order to test the applicability of the FIAM/BLM in particular systems and also for its application in monitoring and risk assessment of metals. This review summarises the studies that combine a biological measure of Cu bioavailability with the use of a chemical speciation technique for the measurement of Cu speciation in seawater, and it presents a critical examination of the results of those studies in order to determine which techniques are more suitable for the prediction of Cu bioavailability in seawater and to highlight research needs in the field. The technique showing the highest level of agreement with bioavailability data is anodic stripping voltammetry (ASV). Cathodic stripping voltammetry (CSV), aluminium hydroxide coated exchange resin (ALSA), and diffusion gradients in thin films (DGT) are also promising in this regard, although DGT slightly overestimates bioavailable Cu. More research is needed comparing the performance of different chemical speciation techniques with Cu bioavailability in seawater, especially at environmentally relevant concentrations of Cu.

The effect of copper and chlorpyrifos co-exposure on biomarkers in the marine mussel Mytilus galloprovincialis

Metals and organophosphorous pesticides commonly co-occur in marine environment, but the effect of their mixtures on non-target organisms is still poorly understood. This study investigated the combined effect of the essential metal copper (Cu) and organophosphorous pesticide chlorpyrifos (Chp) in mussels (Mytilus galloprovincialis) after short-term exposure to their sublethal concentrations. Mussels were exposed for four days to 5 and 15 μg L−1 Cu and 0.05 and 5 μg L−1 Chp, and to their binary mixtures. The investigated biomarkers, namely acetylcholinesterase activity (AChE), glutathione S-transferase activity (GST), metallothioneins content (MTs) and lipid peroxide levels (LPO) displayed unspecific and inconsistent response patterns that varied depending on the concentration of chemicals and composition of mixtures. The exposure to Cu or Chp alone did not induce AChE activity changes, whereas only Cu provoked a significant GST activity increase. Exposure to lower and higher concentration of Chp resulted in MTs content and LPO level increase, respectively. Response of biomarkers to mixtures was generally inconsistent. Data integration by IBR index and PCA revealed different stress levels for given exposure conditions, but no explicit differentiation between single and joint exposures was found. The present results showed that low and environmentally relevant concentrations of Cu and Chp in mixtures may result in a detectable biological response, stressing the need for further investigation of joint effects of widespread marine contaminants in sentinel organisms.

Effects of life-time exposure to waterborne copper on the somatotropic axis of the viviparous fish Poecilia vivipara

Reduced fish growth following chronic exposure to dissolved copper (Cu) is well reported in the literature. Nevertheless, information on the mechanism(s) involved in this process is scarce. Therefore, we evaluated growth, gene expression and concentrations of proteins related to growth regulation in the viviparous guppy Poecilia vivipara chronically exposed to dissolved Cu. Newborn (<24 h after birth) fish were kept under control conditions or exposed to environmentally relevant concentrations of Cu (5 and 9 μg/L) in salt water (24 ppt) for 345 days. After exposure, fish growth was evaluated based on body weight and length. Also, growth hormone (gh) mRNA expression was evaluated in brain, while growth hormone receptor 1 (ghr1) and 2 (ghr2) mRNA expressions were analyzed in brain, skeletal muscle and liver. In turn, insulin-like growth factor 1 (igf1) and 2 (igf2) mRNA expressions were evaluated in skeletal muscle and liver. Additionally, Gh concentration was assessed in brain, while Ghr concentration was evaluated in skeletal muscle and liver. Exposure to 9 μg/L Cu reduced fish body weigh and length. Metal exposure affected mRNA expression only in skeletal muscle. Reduced ghr2 mRNA expression was observed in guppies exposed to 5 and 9 μg/L Cu. Additionally, reduced igf1 and igf2 mRNA expressions were observed in guppies exposed to 9 μg/L Cu. However, no significant change in Ghr concentration was observed. The reduced ghr2 mRNA expression suggests that chronic Cu exposure induced an insensitivity of the skeletal muscle to Gh, thus resulting in reduced igf1 and igf2 mRNA expression which lead to reduced fish growth. These findings indicate that chronic exposure to dissolved Cu disrupts the somatotropic axis regulation, thus helping to elucidate the mechanism underlying the Cu-dependent inhibition of growth observed in the viviparous fish P. vivipara.

Cu and Cd affect distinctly the physiology of a cosmopolitan tropical freshwater phytoplankton

Copper and Cd are natural constituents of freshwater ecosystems, both cycling influenced by microbial communities. The present research examined the impacts of environmentally relevant concentrations of Cu and Cd on the growth, viability, cell size, chlorophyll a (Chl a) content and photochemical efficiency of the tropical freshwater phytoplankton Chlorolobion braunii. Cell growth was significantly impaired by Cu and Cd, with EC50 occurring at 33.6 and 1.6µM, respectively. At sublethal levels (< EC50), cell death was already induced at 5µM Cu and 1µMCd. Average cell volume significantly increased as metal concentrations increased, as did the Chl a content per cell, although the Chl a content per unit volume decreased. Copper did not affect both the photosystem II (PSII) maximum quantum yield (ΦM) or the operational quantum yield (ΦE), while Cd significantly impacted ΦE, with EC50 occurring at 18.4µM. Different responses for Cu and Cd were obtained whether the photochemical fluorescence quenching (Qp) or non-photochemical quenching (Qn) were considered. Qp decreased after Cd addition, but was not altered after Cu addition. Qn values significantly increased after the addition of either metal. Non-photochemical quenching due to heat dissipation (NPQ) significantly increased in response to both metals, but it was more pronounced in the case of Cd. Overall, Cd was more toxic to C. braunii than Cu.

Assessment of health status of oysters (Crassostreagigas) exposed to environmentally relevant concentrations of Ag and Cu in brackish waters

Human activities have altered estuarine environments leading to increased presence of different pollutants including metals. Although the implementation of new environmental policies has caused a considerable decrease in trace metal concentrations in estuaries around the Bay of Biscay, some elements such as copper (Cu) and silver (Ag) are still present in relatively high concentrations. Oysters have been widely used in environmental biomonitoring programs as sentinel organisms. Oysters Crassostrea gigas from an uncontaminated estuary were exposed to sublethal, environmentally relevant concentrations of Cu (2000ng Cu/L) and Ag (500ng Ag/L) during 14days in brackish water (S=18). A battery of cell and tissue level (exposure) biomarkers at different levels of biological complexity was applied and integrated into the Integrative Biological Response (IBR) index including: metallothionein contents, intralysosomal metal accumulation, digestive gland atrophy and digestive gland tissue integrity. Condition Index (CI) was incorporated into the IBR index as a complementary parameter that reflects the general physiological condition of oysters (organism level). Results indicated an increase in intralysosomal metal accumulation after 7 and 14days of exposure to Ag together with an increase in the digestive epithelium atrophy and lipofuscin content after 7days of exposure to Ag. The responses detected with the aid of biomarkers integrated in the IBR index showed higher toxicity in oysters exposed to Ag, inducing the clear onset of detoxification processes which also occurred, to a lower extent, in Cu-exposed oysters.

Kinetics of Deposition, Acute Toxicity and Bioaccumulation of Copper in some Freshwater Organisms.

Experiments with environmentally relevant concentrations of Cu in glass aquaria revealed that Cu was quickly removed from water. Cubic regression of Cu concentration against time showed that maximum rate of removal was around 69.34-72.11h irrespective of treatment. The 96h LC50 value of Cu was respectively 0.18, 0.19 and 0.35mg/L for fish Cyprinus carpio, crustacean Diaptomus forbesi and worm Branchiura sowerbyi. Normalizing the lethal values and plotting them against time it was observed that there was sharp differences in mortality over time between the organisms and 96h lethal values could misrepresent susceptibility of the organisms to Cu. Treatment of 0.1mg/L of Cu in water resulted in accumulation of 10.57, 4.38, 1.46 and 2.44µg/g of Cu, respectively in sediment, worm, crustacean zooplankton and whole body of fish. But, Cu deposited in high concentrations in gut and liver of fish indicating that Cu was principally accumulated through food.

Assessment of the effects of Cu and Ag in oysters Crassostrea gigas (Thunberg, 1793) using a battery of cell and tissue level biomarkers

Oysters are considered sentinel organisms in environmental water quality monitoring programs in which cell and tissue level biomarkers are reliable tools. Copper (Cu) and silver (Ag) are present in relatively high concentrations in several estuaries, potentially affecting environmental and human health. Crassostrea gigas oysters were exposed during 28 days to a range of environmentally relevant concentrations of Cu and Ag alone or in mixture. Effects were studied through cell and tissue level biomarkers approach. Results indicated: changes in the Condition Index (CI), altered digestive gland epithelium and presence of histopathological alterations in the gonad and digestive gland of exposed oysters. A time-dependent increase in lipofuscin contents in exposed oysters and an increase in intralysosomal metal accumulation in digestive cells through the experiment were also recorded. The Integrative Biological Response (IBR) Index showed that even at low exposure levels, Ag and Cu can produce alterations on oysters' health status.

Twice as easy to catch? A toxicant and a predator cue cause additive reductions in larval amphibian activity

Toxicants may harm predators or prey differentially, hindering clear determination of multiple stressor effects on predation dynamics in polluted aquatic systems. We built on a prior field study in which we demonstrated that a chemical contaminant, copper (Cu) and odonate predators were correlated with more frequent observations of skeletal abnormalities in Alaskan wood frog (Rana sylvatica) tadpoles. Our prior study established a multiple stressor effect linked to an important environmental phenomenon (malformed amphibians) but did not provide clear mechanisms that might guide management. We here investigated behavioral mechanisms because of their potential to produce large changes in predation dynamics, and because in published studies low concentrations of Cu produced behavioral changes in predator-detection in fish. Surprisingly, low but environmentally relevant concentrations of Cu (5 μg/L) combined with chemical cues from a predator (Aeshna sitchensis) to produce large changes in the behavior of larval amphibians. Experiments demonstrated that a low concentration of Cu did not inhibit the ability of wood frog tadpoles to detect chemical cues of predators by olfactory means, but produced strong behavioral effects, causing tadpoles to reduce activity and alter microhabitat use. These results occurred with Cu at an exposure level lower than any we could find reported as toxic to amphibians in the literature. When Cu and predator cues were administered together, the activity reduction was additive and stronger at earlier life stages. We suggest that Cu intoxication would be disadvantageous to larval amphibian prey with prolonged exposure to predators during development, and we present field data from 2010 that support this assertion. Our study demonstrates the need to use sensitive behavioral assays and to investigate multiple stressor mechanisms to understand how multiple threats combine to affect organisms in nature.

Oligomeric assembly of native-like precursors precedes amyloid formation by beta-2 microglobulin.

The deposition of beta-2-microglobulin (beta2m) as amyloid fibers results in debilitating complications for renal failure patients who are treated by hemodialysis. In vitro, wild-type beta2m can be converted to amyloid under physiological conditions by exposure to biomedically relevant concentrations of Cu(2+). In this work, we have made comparative measurements of the structural and oligomeric changes in beta2m at time points preceding fibrillogenesis. Our results show Cu(2+) mediates the formation of a monomeric, activated state followed by the formation of a discrete dimeric intermediate. The dimeric intermediates then assemble into tetra- and hexameric forms which display little additional oligomerization on the time scales of their own formation (<1 h). Amyloid fiber formation progresses from these intermediate states but on much longer time scales (>1 week). Although Cu(2+) is necessary for the generation and stabilization of these intermediates, it is not required for the stability of mature amyloid fibers. This suggests that Cu(2+) acts as an initiating factor of amyloidosis by inducing oligomer formation. (1)H NMR and near-UV circular dichroism are used to establish that oligomeric intermediates are native-like in structure. The native-like structure and discrete oligomeric size of beta2m amyloid intermediates suggest that this protein forms fibrils by structural domain swapping.

The interaction of copper(II) and glycyl-l-histidyl-l-lysine, a growth-modulating tripeptide from plasma

The interaction between Cu(II) and the growth-modulating tripeptide glycyl-L-histidyl-L-lysine in the presence and absence of L-histidine was investigated by potentiometric titration and visible-absorption spectrophotometry at 25 degrees C in 0.15 M-NaCl. Analyses of the results in the pH range 3.5--10.6 indicated the presence of multiple species in solution in the binary system and extensive amounts of the ternary complexes in the ternary system. The species distribution and the stability constants, as well as the visible-absorption spectra of the species, were evaluated. The combined results were used to propose the structure of some of the complexes. The influence of the epsilon-amino group of the peptide in the enhancement of the stability constants was reflected prominently when compared with those complexes formed by either glycyl-L-histidine or glycyl-L-histidylglycine. The results obtained from the equilibrium-dialysis experiments showed that this tripeptide was able to compete with albumin for Cu(II) at pH 7.5 and 6 degrees C. At equimolar concentrations of albumin and the peptide, about 42% of the Cu(II) was bound to the peptide. At the physiologically relevant concentrations of Cu(II), albumin, L-histidine and this peptide, about 6% of the Cu(II) was associated with the low-molecular-weight components. This distribution could be due to the binary as well as the ternary complexes. The possible physiological role of these complexes in the transportation of Cu(II) from blood to tissues is discussed.